My worst fear is what’s sitting on the other side of the wall. I keep my eyes shut and try to identify all of the different smells and sounds in this warehouse. I found the grave because of the musty odor. I found the wall because of the sound—which I’m pretty sure is a refrigerator.

He’d need one to keep the chemicals he uses in his knockout drug. This one sounds big, like it has a freezer. I can only think of one thing he’d need that much space for behind a secret wall: a body.

Chloe is probably just a few feet away from me. Pulled from life, then dug from the ground so she could be stashed away for her twin to take her place, she’s now shoved into a refrigerated cabinet like some kind of lab specimen.

Did the Warlock put her there so he could go look at her body? Is it some kind of sick thrill for him to walk over to his secret room and stare down at the body of his first victim?

Did Denise know when she was dying, trying to climb out of the ground a hundred feet away, that her twin was already here?

Underneath the smell of wet dirt, concrete and rust is an acrid odor. It’s not machine oil or the thousand other scents you find in a garage. This is a fuel smell, like a high-octane propellant. The scent of dragsters and jets.

There’s also the slightly rotting odor of fertilizer . . .

Jet fuel and fertilizer. A less lethal combination took out half of an Oklahoma federal building. Behind me is enough space for a hundred trucks’ worth of bombs.

How much would the Warlock need? The purpose of the explosion wouldn’t be just to kill any investigators, it would also be to remove any trace of evidence.

During our briefing Shannon explained that on one side of the property is a factory where women toil away at making police uniforms. On the other is a machine shop where a dozen blue-collar men and women work every day. They’re at work right now, with no idea what’s going on next door.

A bomb this big would leave a crater the size of a block. They’d all be gone. How many people? Fifty? A hundred?

My mind races with all of the disturbed possibilities. I try to keep my pulse down so my chest doesn’t start heaving and set off the sensors. If he sees me here, I’m not sure I’ll make it to the rollup door before he can press a button.

To some, the lives we’ve seen lost so far don’t seem as consequential in the devil’s arithmetic. I have a new reason to remain motionless: It’s not just my life, it’s everyone around me.

On the other side of the fence, Danielle, Shannon, and all the agents and police who are waiting for me would be taken out in the blast.

One twitch, one sneeze and the sensors go off.