Chapter Summaries

Ernie, Hannah, and Hermione gathered clues about the Christmas-night dungeon disturbances, and Moody used them to identify a seventh-year Hufflepuff as their target. While Moody ordered surveillance, Sirius complained that Harry had used cunning rather than a direct fight, and Douglas accepted that Harry was becoming like him.

• Ernie and Hannah got the Fat Friar to describe strange magical residue near the dungeons, while Hermione's team learned of red dust outside Snape's door.
• Moody connected the clues to inferior Floo Powder and salamander blood powder, then matched the incidents to a Hufflepuff seventh-year's book borrowing and Christmas-night movements.
• Moody ordered the students to watch the suspected Hufflepuff without contact and learn his routes, associates, and locker contents.
• Sirius criticized Harry for humiliating Snape and maneuvering Malfoy into the fallout instead of confronting him directly.
• Douglas reminded Sirius that he was Harry's uncle, and Sirius lamented that Harry was becoming like him.

Harry and Ron surveilled a kind Hufflepuff student, but Moody convinced Harry that the student's helpfulness was a calculated disguise. Moody then ordered Harry and Ron to stage an accidental collision and test the student with an enchanted Knut.

• Harry watched the Hufflepuff student help a lost first-year and began doubting that he was the criminal Moody described.
• Harry reported his doubts to Moody, who called the student's kindness a performance and praised Harry's observations as evidence the investigation was working.
• Moody ordered Harry to continue watching the student and described a pressure test involving direct contact.
• Moody assigned Ron to spill the student's belongings in a crowded corridor and Harry to use an enchanted Knut to check them for traces of powdered salamander blood.

Harry and Ron tested a seventh-year Hufflepuff with the Knut but got no reaction, leaving the Detective Club convinced their investigation had failed. Moody reframed the result as a successful elimination of a false lead, and the group renewed its faith in him.

• Moody told Hermione that staging an accidental collision would test the Hufflepuff without making him suspicious.
• Harry and Ron collided with the seventh-year Hufflepuff in a crowded corridor, scattering his belongings.
• Harry touched the Hufflepuff’s wand, book, and robe pocket with the Knut, but it stayed cold.
• Harry reported the failed test to Moody at the Charon Detective Agency headquarters.
• Moody declared the operation a success because it had disproved a false lead, and the Detective Club members admired his reasoning.

Moody abandoned his plan to use Harry Potter to investigate what went missing from Snape’s office and recruited Draco Malfoy to uncover the secret instead. Malfoy accepted the challenge and resolved to prove his worth to Holmes by bringing him the answer himself.

• Moody called off the Detective Club’s investigation for the day and prepared to pursue a new approach.
• Snape rejected Malfoy’s attempt to explain himself, leaving Malfoy humiliated and furious.
• Moody told Malfoy that Holmes valued usefulness and challenged him to identify what he could offer that Harry Potter and Hermione Granger could not.
• Moody urged Malfoy to use his Slytherin connections to investigate what went missing from Snape’s office and uncover a larger secret.
• Moody left the task to Malfoy, who resolved to find tools, complete the investigation, and bring the results to Holmes.

Douglas Holmes met Snape at midnight to apologize for the trouble caused by the missing ingredients and enlist Snape in his plan. Snape took Douglas’s replacement gift, an obsidian ring, and wore it to breakfast the next day.

• Snape found Douglas’s note in his office and agreed to meet him at the Forbidden Forest at midnight.
• Douglas apologized for the missing Bicorn horn and African Tree Snake skin, and Snape accused him of causing trouble and pursuing a grand plan.
• Douglas told Snape he was being watched and suspected, then gave him an obsidian ring as a replacement Christmas present.
• Snape accepted the ring and agreed to keep playing a suspicious Head of House while Douglas handled the rest.
• The next morning, Hogwarts students and teachers noticed Snape wearing the black ring on his left index finger.

Draco Malfoy planted an Echo Moth in Snape’s office and mistook Snape’s staged behavior for evidence of wrongdoing. Moody praised Draco and recorded his reports, preparing to use them to mislead the other students.

• Draco used the family creation Echo Moth to listen in on Snape’s office and heard broken remarks about betrayal and trust.
• Draco reported the conversation to Moody, who urged him to watch Snape closely in Potions class for visual evidence.
• Snape deliberately spoiled a batch of Shrinking Solution and ordered the class to keep the incident secret, convincing Draco that he was destroying evidence.
• Draco told Moody that Snape had ruined the potion in a suspicious fit, and Moody praised him for proving his value.
• After Draco left, Moody copied the reports into a parchment record and planned to feed the material to the student detectives.

Moody was about to expose the supposed mole when Sirius’s Howler announced that the delayed joint monthly exams would begin the following Monday, forcing the Charon Detective Agency to abandon its investigation for revision. Douglas revealed that he had prepared the exams and told Sirius to let the spell continue a little longer, leaving Moody’s revelation on hold.

• Moody gathered Harry, Ron, Hermione, Ernie, and Hannah in his office and prepared to identify the real mole using Malfoy’s report.
• Sirius’s Howler announced that the December Joint Monthly Examination would cover all term material, suspended club activities, and ordered everyone to revise.
• Hermione dropped the investigation and began packing her schoolbag to prepare for the exams, while Harry and the others worried about their revision.
• News of the exams spread through Hogwarts, alarming Viktor Krum and Fleur Delacour and prompting Fred and George to sell study aids to international students.
• Sirius laughed at Moody’s ruined plans while Douglas marked the exam papers and said Moody would have to wait longer for the truth.

As Hogwarts students turned their attention to monthly exams, Snape prepared a punishing Potions test while the Detective Club’s investigations faded into the background. Draco Malfoy began Moody’s discreet observation mission by approaching Snape with a fabricated question.

• Snape decided to stop pretending to be overwhelmed and picked an advanced toxicity textbook to help prepare his exam.
• Harry returned to his dormitory feeling overwhelmed by the investigation, the upcoming exams, and a mountain of textbooks.
• Students packed the library and reviewed for exams as Professor Flitwick declared that everything taught, untaught, or illustrated in the textbook could be tested.
• Hermione offered Ron her knowledge framework diagram instead of letting him copy her notes, while Harry and Ron struggled to study.
• Professor Douglas named three supposed free-point exam topics, which Hogwarts students marked as dangerous, while Krum and Fleur studied them eagerly.
• Draco Malfoy entered Snape’s office on Moody’s assignment and posed an intentionally foolish question about brewing Sopophorous Beans.

As Hogwarts, Durmstrang, and Beauxbatons began their joint monthly exams, Harry remained focused on Moody’s secret mission rather than his studies. He eagerly tackled Professor Holmes’s Defense Against Dark Magic exam, which ended with a forty-mark strategic analysis question.

• Snape ordered Malfoy to copy a passage a hundred times, humiliating him for neglecting his studies.
• Hermione noticed Harry secretly studying a map and suspected Moody was driving a wedge between him and Ron.
• The night before the exams, Harry decided to finish his papers quickly so he could resume watching for the mole.
• Students from Hogwarts, Durmstrang, and Beauxbatons sat the exams together, beginning with Snape’s difficult Potions paper and McGonagall’s detail-heavy Transfiguration exam.
• Harry confidently answered the theory and combat-simulation questions on Professor Holmes’s Defense Against Dark Magic paper before reaching a final question worth forty marks.

Harry treated the exam question about a leaked investigation as validation of his open-conspiracy strategy, while Hermione used the same question to reconsider Moody’s actions. She concluded that Moody was not investigating but deliberately fomenting chaos, and the chapter ended with her seeing his approving grin as a monster’s smile.

• Harry recognized the exam question as his earlier plan and began writing in defense of strategy A.
• Hermione connected Harry’s secret tasks, Moody’s anger at enforced silence, and his approval of public exposure, concluding that Moody’s actions contradicted an investigator’s instinct for control.
• The exam ended, and Ron invited Harry and Hermione to celebrate with Pumpkin Pasties.
• Hermione remained frozen and stared at Moody as he collected the papers, seeing a monster beneath his heroic appearance.

After the Monthly Exams, Harry told Hermione and Ron that Moody had assigned him to investigate Snape and Karkaroff in exchange for teaching him advanced Auror magic. Hermione argued that Moody’s story was a false lead and accused Moody of being the real thief, leaving Harry furious and storming out.

• Harry revealed that Moody had privately assigned him to investigate Snape and Karkaroff and had claimed both were former Death Eaters.
• Hermione and Ron questioned why Snape or Karkaroff would steal ingredients, and Hermione concluded that Moody might have invented the story to distract them.
• Hermione told Harry she suspected Moody was the real thief.
• Harry angrily rejected Hermione’s accusation, and Ron struggled to choose between their arguments.
• Harry slammed the door as he left, while Hermione stood despondently and Ron remained silent.

Hermione brought her suspicions about Moody to Professor Douglas Holmes, but he praised her analysis and refused to intervene, insisting the Detective Club had to handle its own case. Undeterred, Hermione asked Ron to use Arthur Weasley's Ministry connections to investigate Moody’s background, and Ron agreed to write to his father.

• Hermione spent the night analyzing Moody’s behavior and concluded that she needed an adult’s help investigating him.
• Hermione presented her suspicions to Professor Douglas Holmes and urged him to investigate Moody because she feared Harry and Hogwarts were in danger.
• Douglas praised Hermione’s reasoning but said he would remain an observer and assessor, leaving the Detective Club to solve its own case.
• After leaving Douglas’s office, Hermione decided to investigate Moody’s background herself and approached Ron for help.
• Hermione asked Ron to contact Arthur Weasley through the Ministry of Magic, and Ron agreed while warning that Moody was a Ministry legend.

Hermione struggled to prove that Moody was an impostor, but Arthur Weasley's letter and Moody's impeccable record left her isolated and doubtful. After reconsidering the possibility that Moody was genuine, she found old newspaper reports revealing how Karkaroff and Snape had avoided punishment, and formed a chilling new theory.

• Ron gave Hermione Arthur Weasley's letter describing Moody's heroic Auror career and urging them to value his guidance.
• Hermione remembered that Moody repeatedly caught her following him, while Harry, her friends, and Professor Douglas offered no help.
• After reading that Moody was paranoid about Dark Wizards, Hermione wondered whether he was the real Moody and began investigating Snape and Karkaroff.
• Hermione found a Daily Prophet report that Karkaroff had been acquitted after identifying Death Eaters, including Augustus Rookwood.
• Hermione found a report that Dumbledore had vouched for Snape in court, claiming Snape had spied for their side, and she formed a new theory.

Hermione warned Snape that Moody was targeting him and Karkaroff through vigilante justice. Snape realized Douglas and Dumbledore had suspected Moody and used him as bait, and Hermione left believing her warning had reached him.

• Hermione inferred that Moody was pursuing people he believed guilty and went to Snape's office to warn him.
• Hermione explained her theory to Snape and showed him an old newspaper, without mentioning that she suspected Moody was an impostor.
• Snape connected Hermione's warning to the Ouroboros ring Douglas had given him and concluded that Douglas and Dumbledore had known Moody was dangerous.
• Furious that he and Harry had been used as bait, Snape shoved Hermione out and slammed the office door.
• Hermione left the dungeon, realizing that Snape had understood her warning and turned his anger toward the real enemy.

Douglas explained to Snape that the Moody impersonation was meant to teach Hogwarts students caution and lure Voldemort into revealing his plans. Snape joined the scheme after using the Ouroboros ring to suppress the pain in his left arm, demanding that Douglas protect Harry.

• Snape confronted Dumbledore and demanded to know what Alastor Moody was, then accused Douglas of placing him and Harry in danger.
• Douglas admitted he was using Snape and Harry to teach students about misjudging people and explained that the plan was also meant to draw Voldemort out.
• Dumbledore teased Douglas about his grudge against Moody, who had once tried to recruit him as an Auror.
• Douglas revealed that the controlled crisis was intended to make Voldemort believe his Hogwarts agent had everything under control and expose his next move.
• Snape put on the Ouroboros ring, which stopped the pain in his left arm, and agreed to join the plan on the condition that Douglas protect Harry.
• Snape left without shaking Douglas's hand, and Dumbledore observed that the strongest alliances did not need one.

After the monthly exams, Harry reported his vigilance to Moody, who praised him and assigned him to discreetly watch Snape and Malfoy. Harry left convinced he had become an undercover Auror Apprentice, with Snape and Malfoy as his targets.

• After the monthly exams ended, Harry turned down Ron’s invitation to celebrate and hurried to Moody’s office to report that he had watched Snape and found nothing suspicious.
• Moody praised Harry for staying vigilant, then warned that the lull after exams could be dangerous.
• Moody told Harry that Snape was secretly connected to his trusted student, Draco Malfoy, and Harry agreed with the suspicion.
• Moody gave Harry parchment and a quill and ordered him to discreetly record every abnormal interaction between Snape and Malfoy.
• Harry accepted the assignment and left Moody’s office believing he had become an undercover Auror Apprentice.

Snape confronted Douglas Holmes about whether he had written the Half-Blood Prince story, but Douglas denied it and turned the questioning back on him. Snape’s furious reaction revealed how deeply the story had struck him, while Douglas remained behind, pleased with his prank.

• Snape left the dungeons, suspecting Douglas Holmes had written the Half-Blood Prince story after the meeting in Dumbledore's office.
• Snape hid in a suit of armor’s shadow and stopped Douglas with an Impediment Jinx as he walked past.
• Snape asked Douglas whether he had written the story, and Douglas denied it while claiming he did not read gossip tabloids.
• Douglas suggested Snape feared the article referred to a person Dumbledore had mentioned, prompting Snape to angrily order him to stop speculating.
• Snape fled toward the dungeons, and Douglas watched him go with a pleased smile.

Professor Douglas taught the students how camouflage could make something seem like it naturally belonged, then warned that behavior that never seems out of place could signal a hidden director. Harry took the lesson as confirmation that Snape's familiar nastiness concealed his real motives, while Hermione began to suspect that Moody's heroic image might itself be a carefully constructed script.

• Douglas unveiled tanks of camouflaged magical creatures and organized a classroom game to find them.
• Harry and Ron found a Puffskein disguised as a curled leaf, while Hermione's group used faint air currents to win the game.
• Douglas explained that the most effective disguise made observers accept something as natural, and warned that a presence that never seemed out of place was dangerous.
• Harry concluded that Snape's established behavior was camouflage for lurking at Hogwarts and trusted Moody's theory more strongly.
• Hermione connected Douglas's warning about a perfect script to Moody's seemingly flawless heroic persona and looked at Douglas with alarm.

During a Defense Against Dark Magic lesson, Professor Douglas used a story from his school days to warn Harry and the others about confirmation bias. Harry was left uneasy as he recognized similarities to Moody’s request to investigate Snape and Malfoy.

• Douglas led the students through a chaotic exercise using Summoning Charms to flip over Fire Crabs, then advised them to think about why their spells had gone out of control.
• Douglas casually asked Harry about the Detective Club, and Harry vaguely said they were still observing.
• Douglas told the students that a Potions professor had once falsely accused a Transfiguration professor of stealing a Mandrake, leading Douglas to gather evidence against an innocent teacher.
• Douglas revealed that the Mandrake had been safe in the Potions professor’s greenhouse and that the accusation had been a prank, prompting the students to laugh.
• Douglas explained confirmation bias and warned that people could fit evidence to a conclusion instead of letting evidence guide them; Harry felt uneasy about Moody’s instructions.

Douglas explained that his mandrake story was a fictional example of confirmation bias, while McGonagall and Snape challenged him over its resemblance to their history. Moody took the public dispute as further evidence of Hogwarts’s factions and resolved to uncover Douglas’s secrets before the Triwizard Tournament’s second task.

• Hermione recognized that Moody was exploiting Harry’s confirmation bias, but Harry dismissed Douglas’s warning and took it as a test of his resolve.
• McGonagall challenged Douglas at lunch, saying she had never argued with Snape over Herbology materials.
• Snape demanded to know where Douglas had found inspiration for his story about their supposed disagreement.
• Douglas said the story was fictional and used to teach confirmation bias, comparing it to explaining dragons without bringing a Hungarian Horntail into class.
• Moody observed the professors’ reactions and decided to investigate Douglas’s hidden abilities before the second task.