Sixteen times six

"It takes about five hours to get from here to Sherrinford. Eurus can't be trusted completely. If anything happens in the meantime-and I mean if-please, no matter what, stay alive."

Eurus had caused major disturbances at the prison before, but never on a scale like today's. After lying low and planning carefully for so long, she was probably ready to fight Sherlock to the death this time.

"Memories. What's in those memories? You just mentioned the playroom. Right, our secret base, the playroom."

"We can't move this pump. Its outlet is welded to the mouth of the well, and the bomb on the vehicle is a military-grade pressure bomb. It'll explode immediately even if we move it half a centimeter. Our only option right now is to disarm the bomb, then move the vehicle and rescue John Watson."

The rescue agent informed Mycroft and Sherlock of the situation. The manor and the prison were in the same direction, so the two had set out together. It would take about another hour to fly straight to the manor, and Sherlock's only hope was to solve the puzzle quickly aboard the helicopter.

Sherlock closed his eyes and forced himself back to that sweltering summer filled with the sound of cicadas.

The images in his memory came with a searing sensation of heat. The sunlight had been harsh that day, and the overpowering scent of the roses blooming along the manor wall had been enough to make him sick and drive the bees wild.

Yes, all three of them had been in the playroom then.

Sherlock's fingertips trembled slightly as he continued to remember.

Little Victor had loved to show off, usually by sharing some army drill his father had just taught him. His incessant chatter had been a great annoyance to the two Holmes children.

The image focused on the dim playroom. A young Sherlock huddled in a corner, trying to play a favorite nursery rhyme on a child-sized violin, but he wasn't very good, and the noise he made was piercing.

Beside him, Victor was clumsily trying to build a fortress out of blocks, making booming cannon noises as he worked.

And Eurus... Eurus sat quietly by the window, fiddling with a set of complex geometric puzzles. But her gaze kept drifting toward the two boys as they argued, with an unsettling intensity.

Sherlock hadn't understood what a genius was back then. He had only thought that it wasn't a look a child should have.

"An argument... We had an argument. Why?" Sherlock murmured, his fingers tapping unconsciously against the helicopter's window.

"What did Victor do? What did he say?" Then a muffled scream came from the depths of his memory, not of fear, but of anger.

Victor's voice rang in his ears, taunting him in the shrill tone of a boy: "Monster! Your sister's a monster! My dad said so. The way she looks at people is really scary. Maybe she isn't even human!"

"Monster! Eurus is a monster. I have matches, and I'm going to burn you to death!" The shouting was followed by a dull impact that set his teeth on edge.

Sherlock's eyes flew open, his pupils contracting rapidly to pinpoints. His blue irises had turned gray.

Beep, beep. A video was sent to both their phones at once.

On the screen was a blurry, shaky clip of surveillance footage, apparently from an antiquated security system that had long since been phased out.

The picture quality was terrible, but the actions of the people in it were clear enough. Young Victor kept pointing at Eurus and shouting excitedly. Through the damaged audio, words like "monster" could still faintly be made out.

Seeing that everyone was ignoring him, Victor immediately tried to snatch the violin from Sherlock's hands. At that very moment, Eurus, who had been as quiet as a doll, grabbed the heavy brass telescope beside her with astonishing speed and smashed it into the back of Victor's head.

"Bang!"

The dull impact was clearly audible even through the distorted recording. Victor pitched forward like a puppet with its strings cut, slammed heavily into the pile of blocks, and lay motionless.

Blood quickly spread across the pale carpet. Young Sherlock froze, and the violin clattered from his hands to the floor, its bow breaking in two.

He stared in horror at the deadly telescope, now held in Eurus's slender little hands. She didn't check on the fallen Victor, but simply looked at her terrified brother with indifference.

"Cough, cough, cough-help me! They've started letting water in!" The pump at the mouth of the well had been switched on by an infrared remote. It was humming now, sending a light shower of water trickling into the well. The flow wasn't heavy, but before long it had reached Watson's waist.

"Sir, the protective casing on this bomb can't be removed. It can only be unlocked by entering the code!"

Hearing the person they were rescuing screaming his lungs out below, the rescue workers on the surface began to panic.

"The code, Sherlock. Think carefully. Did you and Eurus have any secret numbers or anything like that?"

Sherlock's throat tightened. The urgency of the present and the fragments of memory collided wildly in his mind, forming scattered pieces of a body. "A secret number, a secret. Yes-"

"You have to play it like this, Sherlock. You're holding your hand wrong!" He remembered now. His little sister had taught him to play the violin, guiding his hands herself.

"Sixteen times six, sixteen times six..." Sherlock clutched his head and murmured to himself.

"Help! I'm starting to float!"

Watson was in serious trouble. The enormous buoyancy of the water was gradually lifting him toward the pump head. If he rose any higher, he would become trapped against the outlet and be suffocated by the flow.

The rescue workers standing guard outside were setting up a cutter, preparing to cut the pump away from the mouth of the well first.

"What is that...?" Watson spread his arms in the water to keep himself steady. Something appeared in front of him, bobbing up and down.

"Good Lord, it's a human skull!" Judging by its size, it belonged to a child. There was a clear crack in the back of it; the child must have suffered a tremendous blow while alive.

"Sir, Mr. Watson found an entire skull in the well, the size of a ten-year-old child's!"

"The code is 1622696."

Beep, beep, beep-

"The bomb's disarmed! Start cutting the steel plate, quickly!"

When Mycroft arrived and got out, no one came to meet him. The rescue workers had no time to spare for their boss. They had just gone to enormous trouble to cut through the special steel plate wedged between the mouth of the well and the pump truck's connector, rescuing their target after a close call. They were now warming Watson, who had just been pulled out, and replenishing his energy.

There was no time, so Sherlock stayed in the helicopter. He gripped the handrail and leaned halfway out, only sitting back down once he saw from a distance that Watson had been rescued.

"That's Sherlock. He just cracked the bomb's disarm code, and now he's going to save Sitangna." Worried that Watson didn't know, Mycroft pointed him out.

Watson was frozen stiff, and his limbs were too cold for him to coordinate their movements, but he still waved in that direction.

I'm all right now. Go save Nana.