“You have to take the children away,” he said. “Vesper will never stop. Even with my new strength, I can’t fight an entire barony. Our best hope is to get far away from him and convince him that my research went up in flames so it’s beyond his reach forever.”

“But the research is in your head, Gideon. How will you get away —”

Gideon leaned forward and kissed his wife. She smelled of wholesome things: sunlight and clean wool, fresh baked bread and rose petals. He had not told her just how sick he was. It was all he could do to stay on his feet, to control the trembling in his limbs. Even if he finished the serum, he doubted it would be in time. His heart was near breaking, but he managed a smile. “Trust me, sweetheart. We will all be together again.”

Before he could lose his nerve, he turned and walked toward the house, where his laboratory waited.

It was near midnight when Gideon realized he would not live to see the dawn.

He’d spent the entire day collecting his equipment, accounting for every scrap of research. He’d kept out only the essential beakers and distillation equipment for the final iteration of the serum. Every so often he’d turn and watch the drops of fluid traveling through the glass tubes with painful slowness. He wished he could speed the process, but there was simply no way.

In the meantime, he had prepared his last line of defense. He’d mixed niter, coal, and sulfur, pitch and acid — using all his alchemical training and his newfound quickness to create one final, deadly compound. Now sealed vats of explosive were placed around the laboratory, strung together with fuse wire of gunpowder-coated rope. On the table, his oil lamp burned with a low blue flame. A windup timepiece turned gears that held the end of the fuse, bringing it ever closer to the fire.

In the morning, Gideon would visit Damien’s manor again. Hopefully, the serum would be done by then, and Gideon would be healthier, ready to take on his old friend. He would try to keep Damien engaged in negotiations for at least an hour — enough time for his family to get a head start on the mainland. Eventually, Damien would grow impatient and demand to see Gideon’s lab. Gideon would stall as long as possible, then reluctantly agree. If his timing proved correct, they would be almost to the laboratory when the time-delayed fuse ignited. Twenty explosive vats would erupt simultaneously, turning the house into an inferno, reducing this lab to a mound of ashes. There would be nothing left for Damien to find.

Perhaps Gideon could escape somehow later on, bide his time pretending to work for Vesper. He could find a way to reunite with his family eventually. Or if not … he would do whatever he must to keep Damien from getting the serum.

 And the ring. Gideon cursed himself. He’d forgotten to give Olivia the ring, which was almost as important, almost as dangerous as the master serum.

He’d explained its secret to Olivia long ago and warned her that Damien Vesper should never possess it. She’d argued many times that the ring shouldn’t be kept under Lord Vesper’s nose, but Gideon felt he had no choice. He couldn’t let something so dangerous out of his sight. Gideon had told Olivia to downplay the ring’s significance should Damien ever ask about it.

 Tell him it has sentimental value, he’d suggested. Perhaps an heirloom from your family, which you gave to me as a token of our marriage.

Now he would have to give her the ring and hope she could take it to safety.

Gideon looked around one more time, taking stock of the place where he’d worked so many years. The laboratory took up half of the house’s ground floor, but it might as well have been a separate building. A small side door led into the house proper, though Gideon usually came and went through the back exit, which led straight to the meadow. While Olivia and Maria kept the rest of the house well scrubbed and tidy, they were not allowed in the lab. For safety, Gideon forbade anyone but himself to enter. He kept the doors locked, thank goodness. If Maria had had a key for the lab, she might’ve given Lord Vesper much more information.

The lab’s oak-beamed ceiling was low and blackened from years of smoke. Shelves of chemicals and racks of tools covered every bit of wall space. The waist-high worktables were cluttered with bowls and vials, and the room had no chairs. Gideon never sat while he worked. His spirit was too restless. He would pace between projects, checking on several boiling vats at once. Olivia often teased him that he cooked six times more than she did and still couldn’t make a decent stew.

He was about to reset the timepiece, douse the oil burner, and close up the lab when a voice spoke behind him: “Father.”

Luke had slipped through the interior doorway, which should have been impossible. Somehow, he’d managed to undo Gideon’s foolproof bolt system. Now he stood there fully dressed, looking agitated.

“Luke?” Gideon managed. “What are you —”

“They’re coming, Father!”

“What do you mean? Why aren’t you in bed?”

Luke waved the question aside. “Couldn’t sleep, of course. They’re coming! Vesper and his men. You have to …” Luke glanced around the laboratory. He noticed the sealed containers, the fuses, the timepiece and burner, and with unnerving quickness he seemed to understand his father’s plan.

“A time-delay explosion,” Luke said in amazement. “You’ll destroy the house, the formula — everything. But there’s no time for that, now! The enemy is almost —”

A fist pounded on the lab’s exterior door. Gideon’s heart crawled into his throat. His enhanced senses should’ve registered the danger much earlier, but the same serum that had made him formidable was now betraying him, making his mind go fuzzy. Of course he should’ve realized: Lord Vesper had scented his prey. He wouldn’t wait until morning. He would strike while Gideon was still unprepared.

“Luke, get out of here,” Gideon ordered. “Wake the others and sneak away now.”

“Give me the full serum!” Luke pleaded. “I can help you fight!”

 He’s already taken his fourth of the serum, Gideon realized. That explained how he sneaked past the security measures so easily. It explained the swift new cleverness in his eyes — how he had picked out details in a dark room and immediately reconstructed his father’s plan. Luke had always been impetuous, but taking the serum? An unforgivable risk.

Still, at the moment Gideon was glad for his son’s recklessness. It might allow him to save the rest of the family.

The exterior door shook again under the pounding of metal-clad fists.

“Luke, listen to me.” Gideon grasped his shoulders. “Even together, we cannot defeat Vesper and all his men. He has assassins everywhere. I know what I’m talking about. Your only hope is to leave now. Wake the family and get out!”

“But the others won’t trust me!” Luke said. “They never do. And how will you get away?”

Gideon didn’t answer.

Luke’s face paled. Gideon could see comprehension dawning on him. “Father, the master serum … you said it was too dangerous. You meant fatal, didn’t you? You’re dying …?”

“You must protect the family now.”

“But—”

“Go, Luke.”

The door rattled and the hinges creaked.

“I love you, Father,” Luke said, his voice wavering. Then he slipped inside.

Gideon barred the door and reset the bolts. He could hear Luke moving heavy furniture to blockade the other side.

Then the exterior door shattered, and two of Vesper’s guards stepped into the laboratory.

They were both dressed in steel and leather brigandine armor. Vesper’s lieutenant, Balthazar, stood at the right, his sword unsheathed. On the left stood the baron’s executioner and strong-arm enforcer, who went by the name of Craven, though it did not fit his appearance. His eyes were a frightening milky white, and his arms were as thick as fence posts. His battle-ax was flecked with splinters from breaking down the door.

Lord Vesper himself stepped through next, dressed in black robes and chain mail. Damien was older than Gideon by at least five years, but he had no hint of gray hair, nor a wrinkle. The commoners swore Lord Vesper had made a deal with the devil to stay young. If Gideon had been superstitious, he might have agreed. The lord’s curly black mane, handsome face, and dark, hungry eyes had not changed in a decade.

“Good evening, Gideon.” Damien tugged off his gloves and scanned the lab. His eyes fixed on the nearest worktable, where Gideon’s distillation was in progress and his texts neatly stacked. “Thank you for compiling your research for us. It makes things much easier. And that would be the mysterious concoction? Excellent. Balthazar, if you please …”

Before the lieutenant could step forward, Gideon grabbed the end of the fuse wire. He held it within an inch of the burner’s flame.

“Come any closer,” he warned, “and you all die.”

Balthazar snorted and started to advance.

“Wait,” Lord Vesper commanded.

Damien’s keen eyes examined the scene more closely — the incendiary charges, the wires connecting them, the timepiece and burner. Only Gideon’s own daughter Katherine could’ve rivaled Damien for mechanical genius. The baron’s lips curled into a dry smile as he appreciated the trap Gideon had created.

Balthazar waited uneasily, no doubt wondering why he was being held at bay by a crazy old alchemist with a piece of rope.

Damien tutted with disappointment. “Really, Gideon, are you willing to destroy yourself, your family, and your precious research? Would you sacrifice everything you’ve worked for just to thwart me? There is no need for that.”

“I can’t let you have the formula, Damien. It will die with me.”

Damien tried to read his face. Gideon had seen him do this with so many people over the years. No one in his right mind would gamble with Lord Vesper and certainly not try to bluff him. Gideon was not bluffing, but Vesper would have trouble believing that. Self-sacrifice was a foreign concept to the baron.

“Work with me,” Vesper said. “We can both benefit. When I am the most powerful man in the world, you will have every resource at your disposal for your projects. You can eradicate the Black Death, as you’ve always dreamed.”

“And see the world crushed under your boots? No thank you.”

“Your family … I can keep them safe, Gideon. But if you oppose me —”

“Do not threaten them again,” Gideon growled. “They know nothing of my work, and I’ll never let you use them as hostages to force my cooperation. I would rather die.”

“I do not believe you,” Vesper said coldly. “We will take your research. Step aside, and we will spare you.”

 He’s lying, Gideon realized. Damien had come to the same conclusion as he: They were now archenemies. One of them must die. If the lab was intact, Damien was more than capable of understanding the serum notes. He had no need of Gideon. He would simply take what he wanted.

Whatever happened, Gideon was doomed. Even if he survived this night, he would never have time to perfect the master serum. The flawed mixture in his veins was already destroying him. The only thing left was to make his death count — to buy his family a chance at survival and to thwart Damien Vesper’s plans.