He makes ready to go when he senses a presence at the door that leads outside. A withered, once-human wraith stands in the doorway. It grins at Moloch with saw-blade teeth. It performs a small obeisance.

Ah.

This is the source of the ancient magic that has broken the castle wards. This is the source of much of the ancient power that fills the stones of Rookskill. This is the creator of the mechanical monster that lies at Moloch’s feet. Moloch acknowledges the wraith with a respectful nod, one twisted soul to another, and then goes on about his business.

A few minutes later, Moloch catches his newest prey and manages to spell her before she can scream.

CHAPTER 46

Isaac

1942

Isaac didn’t try to fly back through time, his mind was so full. Instead he let himself tumble. When he landed back in the darkened armory, he sat on the cold stone floor before his knight—Bedwyr—cradling the watch and trying to make sense of what he’d just learned. He pulled out the pendant from underneath his collar and examined it, the eternity knot.

The pendant that Isaac wore was the key to the Vault. The Vault, as Leo had cleverly surmised, was anywhere it was called to be, and Isaac knew all that was needed to make that magic happen was the pendant key and the symbol on a wall—any wall—and words asking the door to appear. Mistress Vivienne had said, “The Guardian requires you, door, here and now.”

The armory was deathly cold and as silent as a tomb. Willow had vanished. Isaac looked up at Bedwyr as he contemplated the answer to his most pressing question.

*   *   *

Once, on a bright day when Isaac would have rather been outside, his father, trying to give a philosophy lesson to Isaac, was discussing logic. Isaac sat at the table drumming his fingers, looking out at the blue sky and listening to friends shout as they chased a ball through the street, all while his father kept repeating, “Occam’s razor.”

“Fine,” Isaac said, thinking of a blade, not an idea. “May I go now?”

“It’s the principle you can use to answer any question. Can you repeat it?”

“It’s the, well, sometimes you have to . . . I don’t know.” Isaac was ashamed at having been so inattentive. He sat up and willed himself to listen.

Isaac’s father began again. “This will help you whenever you’re in doubt. Whenever you need to weigh evidence and come to a conclusion. Occam’s razor states that the simplest solution tends to be the right one. It’s not universally true—some problems in the world are complex. But if you break them down, generally, when you need to find an answer try for the simplest solution first.”

*   *   *

Now, sitting before Sir Bedwyr, Isaac applied Occam’s razor to his question.