Chapter Summaries

Sherlock’s forgotten childhood dog prompts questions about his memories, while Eurus’s knowledge of Sitangna leads Mycroft to investigate her surveillance footage. Meanwhile, Oliver learned that the political purge required him to sacrifice his only child.

• Sitangna and Watson teased Sherlock over his childhood curls, and Sherlock wondered why his family photos showed no sign of his childhood dog, Redbeard.
• Watson discovered he had missed Janet’s messages while talking with Sherlock, and Janet hung up as soon as he called to explain.
• Eurus ate dumplings from her family and asked Mycroft to send Sitangna or Watson to visit, revealing that she knew about Sitangna.
• Mycroft ordered David to close Eurus’s cell, then requested access to two months of surveillance footage after she injured her fist punching a drawing on the glass.
• Oliver protested when officials told him about the purge, realizing they expected him to get rid of his only child.

After the Gear Society voted to eliminate Emily, Oliver arranged her escape and stayed behind to face the assassins. News of Oliver’s apparent suicide reached Sitangna, Watson, and Sherlock, who still had no sign of Emily and worried that a major turning point was near.

• The Gear Society ended its meeting with a vote against Emily, and Oliver was powerless to stop them.
• Cuike helped Emily escape through a secret passage and hide in a gardeners’ garbage truck.
• Oliver, poisoned and near death, urged Cuike to take the safe’s contents and protect Emily; Cuike fled with them before the assassins arrived.
• News reports said Oliver had died by poison and that Charlie Andrew had also died in an apparent accident.
• Sitangna, Watson, and Sherlock discussed their failed search for Emily and the approaching major turning point, while Candy warned that their own team should stay alert.

Sherlock confronted Professor Ashton at the Britain Museum and deduced that Ashton had replaced the real Victor Trevor with his own child, whom the organization later poisoned. As Ashton revealed a photograph of young Sherlock beside the real Victor, Sherlock’s connection to Victor became the mystery left unresolved.

• Sherlock, Watson, and Sitangna met Professor Ashton in the museum’s Egyptian gallery, where Sherlock identified him as connected to Victor.
• Sherlock accused Ashton of replacing the real Victor with his own child and explained how the organization’s poisoned equipment had killed him.
• Ashton released a neurotoxin that caused hallucinations, while Watson and Sitangna tried to protect the affected Sherlock.
• Sherlock stopped Ashton’s syringe attack with a scalpel and demanded that Ashton let them leave.
• Ashton opened a hidden compartment in the Anubis statue and showed Sherlock a photograph of the real Victor Trevor standing beside Sherlock as a child.

Sherlock recovered a buried memory of Victor’s disappearance as Ashton tried to manipulate him, but Sherlock, Sitangna, and Watson fought back and attempted to escape. Moriarty’s masked agents ambushed them in the dark, and Watson was dragged into a hidden passage while Sitangna’s fate remained unclear.

• Ashton provoked Sherlock into remembering Victor being swept away by a wave while a military-uniformed man watched from shore, and Sherlock accused Ashton of being responsible.
• Sherlock and Sitangna stunned Ashton with the communicator, sending their location signal, while Watson held Ashton at gunpoint as they retreated.
• Masked agents emerged after the hall went dark and shot tranquilizer darts at Watson and Sitangna, who used items from Candy to revive the group.
• Moriarty addressed Sherlock over the speakers and challenged him with a treasure-hunt clue, then white smoke filled the exhibition hall when time ran out.
• Sherlock heard Sitangna scream and Watson struggle before masked men bound Watson in a shroud and dragged him into a hidden passage.

Moriarty kidnapped Sitangna and took her to a private laboratory, where staff drew a large amount of her blood. After waking restrained in an operating room, she learned she had a new mission to escape the laboratory and began looking for a way out.

• Sherlock found Nana's shattered phone and saw its GPS trace a C along the Thames before it shut off.
• Moriarty's men carried the unconscious Sitangna away by helicopter and took her to a laboratory.
• Sherlock collapsed in the exhibition hall as Mycroft's rescue team arrived, whispering a nursery rhyme about Victor.
• Candy told Sitangna that a specialist had developed an antidote for the neurotoxin and that laboratory staff had taken nearly 400 milliliters of her blood.
• Sitangna learned that her new side mission was to escape the laboratory and discovered that she was held in a room attached to Professor Ashton's laboratory.

Sitangna and Candy discovered that Moriarty had captured Sitangna to study his abnormal attraction to her. As the task neared completion, Sitangna tried to delay leaving and held a stare through the lab glass while Moriarty watched her.

• Candy examined Moriarty’s research notes and learned that he was measuring his reaction to Sitangna.
• Candy explained that Sitangna’s aura affected Moriarty strongly, while his resistance to attraction made him dangerous.
• Sitangna panicked over the possibility of being dissected, and Candy warned that the system could not protect her from close-contact attacks.
• Sitangna saw that her main task was nearly complete and asked for an extension so she could stay longer with Sherlock.
• Candy told Sitangna to stop struggling and revealed that Moriarty was watching her through the glass.
• Moriarty questioned the lab head about Sitangna’s strange behavior as she stared back at them.

Moriarty examined Sitangna to learn what caused the strange stirrings in him, then cut into her without anesthesia to study her reactions. The pain did not give him the stimulation he expected, and he felt a dull ache instead.

• Moriarty dismissed the preliminary tests and asked the person in charge to describe Sitangna’s appearance and personality.
• Moriarty went to the operating table and questioned Sitangna about whether she expected Sherlock to rescue her, while revealing that John had been taken somewhere near the manor.
• Moriarty admitted he wanted to investigate the hormones produced by fear and refused to anesthetize Sitangna before taking a tissue sample.
• Moriarty cut Sitangna, who cried out in pain, and he found that her suffering brought him a faint ache rather than the expected pleasure.

Moriarty cut Sitangna’s arm to frighten her while Watson woke trapped in a freezing well. Mycroft’s agents traced one kidnapper to Sherrinford and found leads on the other, and Sherlock rushed to search for Watson and Sitangna.

• Moriarty took a small skin sample from Sitangna’s arm, and she endured the pain while resolving to survive and kill him.
• Watson woke in a seawater-filled well, failed to climb out, and feared he would freeze before rescue arrived.
• Mycroft’s agents traced the helicopter carrying one kidnap victim to Sherrinford and narrowed down possible locations for the other kidnapper.
• Sherlock woke after nearly three hours, tore off his medical equipment, and took the agents’ leads from Mycroft.

Sherlock recovered memories of his sister Eurus Holmes and learned that she had abducted John Watson and Miss Sitangna. With Watson trapped in a freezing well beneath a bomb-laden pump truck and Sitangna held at Sherrinford, Sherlock and Mycroft raced to rescue them, leaving Sherlock to solve a puzzle about his memories.

• Sherlock pieced together that Victor Trevor had been the child hidden behind his memories of Redbeard and demanded that Mycroft reveal what he had forgotten.
• Mycroft showed Sherlock a family photograph and told him about their sister Eurus Holmes, whose existence Sherlock could not remember.
• Agents reported that John Watson was trapped in a well at Musgrave Manor and that Miss Sitangna’s tracker led to Sherrinford Prison.
• Sherlock ordered Mycroft to rescue Watson while he arranged to enter Sherrinford, but Eurus called and promised Sitangna would remain safe until Sherlock arrived.
• Mycroft prepared to fly to Musgrave Manor and told Sherlock that he would have to solve the pump truck’s one-word puzzle, “memories,” to save Watson.

Sherlock recalled Eurus striking Victor with a telescope as a child and used their shared memories to crack the bomb code, allowing the rescue team to save John Watson. After seeing Watson rescued, Sherlock continued on to save Sitangna.

• Sherlock remembered that Eurus had taught him to play the violin and recalled her striking Victor with a telescope after Victor taunted her.
• A surveillance video confirmed that Eurus had hit Victor, leaving him motionless with blood spreading across the playroom carpet.
• As water rose around John Watson in the well, Sherlock recalled the number sixteen times six and worked out the code 1622696.
• Watson found a child's skull in the well, and the rescue team used Sherlock's code to disarm the bomb and cut through the steel plate.
• The rescue workers pulled Watson from the well, and Watson waved to Sherlock, urging him to save Sitangna.