Andrew Lane - Red Leech

Before Matty or Virginia could stop him, he ran towards the reptiles. Three mouths full of sharp teeth opened, and the sudden hissing nearly deafened him. Without stopping to think, he leaped on to one of the rocks and from there to a larger boulder. It shifted beneath his feet, and he knew that if he slipped then the creatures would be on him in a flash. He jumped, off balance, and saw the reptiles climbing on their hind legs beneath him as he flew through the air, stretching up with their long jaws, hoping to snag his heels.

He landed safely on a patch of open ground. He turned, to find Virginia hurtling towards him. He caught her as she landed, and pulled her to one side so that Matty had a clear area. The reptiles snapped at him as he jumped, one of them using its muscular tail to propel it into the air, but its teeth snapped shut a split-second after he passed. He hit the ground and stumbled, rolling before he could get to his feet.

Without any show of emotion, the three reptiles turned around and started advancing again, their beady black eyes fixed on Sherlock, Matty and Virginia.

“Quick!" Sherlock shouted, and led the way to the wall that separated the enclosure from the outside world. To his right the wall was unbroken all the way down to the ground, but to his left piles of rocks hid its base. He ran along the side of the wall, checking in the space behind the rocks. Nothing! Another patch of open ground, and then a large bush that hid the wall. He pushed it to one side, and his heart leaped when he saw a metal grille, rising from the ground to waist height, hinged on the left, and the simple sliding bolt that secured it.

Then he saw the huge padlock that held the secured bolt in place.

Matty came up alongside him. “Can you blow it apart with the gun?” he asked, holding the Derringer out.

Sherlock considered for a moment. “Unlikely,” he said. “That padlock is massive. The lead balls will probably just bounce off.”

“What about the hinges?”

“Three hinges, two bullets. Same problem.”

Virginia joined them, looking over her shoulder worriedly. “I’m not sure we have much of a choice,” she pointed out.

Matty kicked against the grille. It barely moved under the force of his foot.

Sherlock’s mind was a whirl of conflicting thoughts. Two choices: shoot the reptiles, and leave one still alive, or shoot the padlock and probably waste two bullets. Which choice should he make?

A small voice in the storm of his thoughts asked: “What would Mycroft say? What would Amyus Crowe say?” And, just like back on the train, a voice answered: “When you’ve only got two choices, and you don’t like either of them, make a third choice.”

His gaze wandered across the pool that the three of them had jumped into, and he suddenly remembered the stairs that had led downward, next to the steps that had led up to the balcony. They hadn’t been leading to the grille, because that opened out on to flat ground. They had to lead somewhere else. The pool was on that side of the enclosure, and Balthassar had spoken of watching the reptiles storing their food beneath stones under water. Maybe the steps led to an underground viewing gallery; a subterranean room with a thick glass window looking out into the depths of the pool, so that Balthassar and his guests could watch the reptiles swimming.

But how to break through the glass — if there was glass? It would be thick, to withstand the pressure of the water.

So what he had to do was cause more pressure than the window could stand.

He snatched the Derringer from Matty’s hand. Two triggers, of course, which made sense with two barrels. You’d want to be able to fire them separately. He stared down the barrels. “You used to have one of these,” he said to Virginia. “How did you load it?”

“You pour some black powder down the barrel, then you ram a patched lead ball down on to the powder,” she explained, “being careful not to leave any air gaps between the patched ball and the powder. You then put a percussion cap on the other end of the barrel. Then the gun is loaded and ready to fire.”

“Patched lead ball?” he asked, staring more closely down the barrels. “Ah, yes, the ball is wrapped in paper. That must form a seal.”

“Waxed paper. Why is that important?”

“Because it means it’s airtight,” he said. “At least, for a short time. And if it’s airtight, it’s watertight.”

Before Virginia could say anything, Sherlock turned and ran towards the pond, cocking the twin hammers at the back end of the Derringer as he did so. When he got to the edge he dived, hands held out in front of him, Derringer held in his right hand. The water closed over his head: warm and filled with floating motes of dust and vegetation. Sound was suddenly muffled. He kicked with his feet to take him towards the far wall, beneath the balcony.

And there, where he knew it had to be, where deduction had told him it was, was a glass window set into a metal frame. Before any water could leak into the Derringer he placed it flat against the glass.

And pulled both triggers at once.

Somewhere in the back of his mind was the fact, read once and never forgotten, that water was incompressible. No matter how much you squeeze it, water never gets any denser. All that happens is that the pressure you exert gets transferred elsewhere. Such as to whatever the water is touching.

And so when the hammers at the base of the barrels hit the two percussion caps, the fulminate of mercury inside ignited. This caused the sulphur, charcoal and potassium nitrate in the black powder to burn rapidly, producing a huge volume of hot gas. The gas pushed the lead balls along the barrels, burning the paper patches away as it did so. The bullets pushed against the water in the barrels, and the water pushed against the window.

Which cracked and shattered.

The entire contents of the pond poured into the underground room, taking Sherlock with it. He struck out blindly for the corner of the room where the stairs had to be, hoping desperately that Virginia and Matty would realize what he’d done and follow him. Should he have warned them in advance? It hadn’t occurred to him. He’d just followed through on his deductions without realizing that the other two might not understand.

His lungs were burning with the effort of holding his breath, and his heart was thudding within the cage of his ribs. He pulled himself through the murky water with desperate movements of his arms. Suddenly he felt his knuckles brush against the stone edge of a step. He aimed upward and swam as hard as he could.

When his head emerged from the water, level with the bottom of the doorway that led outside, into the sunlight, he took huge gulps of breath one after the other, waiting for his racing heart to slow.

Matty’s head popped out of the water beside him. Virginia was moments behind.

“You,” Matty said, breathing hard, “are some kind of genius. I don’t know what you did, but you saved us.”

“Not quite,” Virginia pointed out breathlessly.

“What do you mean?” Matty asked.

“Sherlock said those things were amphibious.”

The three of them looked at each other for a long moment, then scrambled rapidly out of the water.

The steps to the underground observation room and to the balcony were out of sight of the house. The three of them sat down for a moment to catch their breaths.

“What now?” Matty asked. “What do we do?”

“Only thing I can think is that we follow the train tracks back to the last town,” Sherlock replied. “There’ll be a telegraph office there. We can send a message to Virginia’s father. We have to tell him about Balthassar’s Army, and the invasion of Canada.”

“Ah,” Matty said, “walking.”