A jolt of shock rushes through me, so fast and buzzing it feels like the bed frame has been electrified. I let go of it and, swaying slightly, stare at the person tied to the bed. A person who is definitely Katherine Royce. It’s the same coltish body, long hair, and billboard-ready smile.

Yet I seem to be the only person here who understands that fact, making me unsure who to be worried about more. Katherine, for making such an outlandish claim, or her husband, for believing it.

“I told you so,” Tom says.

From the bed, Katherine adds, “I know how weird this seems, Casey. And I know what you’re thinking.”

That’s not possible. I’ve just been told my husband, dead for more than a year, is inside the body of a woman I had thought was missing for days. No one else can fully comprehend the chaos of my thoughts.

At least now I understand all of Tom’s secrecy, not to mention his lies. He believed he couldn’t keep Katherine around, pretending everything was normal, when to him, nothing about the situation was normal. So he whisked her to the house next door, away from their glass palace and my prying eyes. He hid her cell phone, posted that sham picture on Instagram, tried as much as he could to keep what he believed to be the truth from getting out.

Because who would have believed him?

I sure as hell don’t.

The idea is more than crazy.

It’s batshit insane.

“This is real, Casey,” Tom says, easily reading my thoughts.

“I believe you think that.” My words are calm and careful—a clear indicator that I’ve made up my mind. Right now, Tom is the more dangerous of the two. “When did you start to think it was happening?”

“Not as early as I should have.” Tom looks askance at his wife’s form, as if he can’t bring himself to completely face her. “I knew something was wrong the day you fished her out of the lake. She was acting weird. Not quite herself.”

It’s exactly the way Katherine described what she thought was happening to her. The sudden weakness. The coughing fits. The fainting. It occurs to me that this could be a form of simultaneous delusion, with one of them influencing the other. Maybe Katherine’s symptoms prompted Tom to start thinking she was possessed, which in turn made Katherine believe it herself. Or vice versa.

“It just kept getting worse and worse,” Tom continues. “Until, one night, it was like Katherine was no longer there. She didn’t act like herself or sound like herself. She’d even started to move differently. I confronted her about it—”

“And I told him the truth,” Katherine says.

I don’t ask when this happened because I already know.

The night before Katherine disappeared.

If I close my eyes, I’ll be able to picture the scene with cinematic clarity. Tom pleading with Katherine as she stood by the window.

Who.

That’s the word I’d struggled to identify.

Who was she?

Len, apparently. An idea preposterous to everyone but the two other people in this basement. Stuck between them, their madness coming at me from both sides, I know I need to get them away from each other. Even though it’s clear Tom’s been feeding Katherine, he’s neglected everything else. A foul odor rises from the bed, indicating she hasn’t been bathed in days. An even worse smell wafts from a bucket in a corner of the basement.

“Tom,” I say, trying not to let my horror at the situation seep into my voice. “Could you leave us alone? Just for a minute?”

He finally looks at the bed and the person he thinks is someone other than his wife. “I don’t think that’s a good idea, Casey.”

“I just want to talk to her,” I say.

Tom continues to hesitate, even though his entire body appears eager to leave. His legs are parted, as if gearing up for a sprint, and he leans slightly toward the basement stairs.

“I won’t be long,” I say. “Katherine’s not going to go anywhere.”

“Don’t untie her.”

“I won’t,” I say, even though it’s one of the first things I plan on doing.

“She’ll ask you to. She’s . . . tricky.”

“I’m prepared for that.” I put both hands on his shoulders and turn him until we’re eye to eye. Knowing that placating him is the only way I’ll get him to leave, I say, “Listen, I know I’ve caused you a world of trouble the past few days. The spying and the police. I’m truly sorry. I didn’t know what was going on, so I thought the worst. And I promise to make it up to you as much as I can. But right now, please, if this is my husband, I want to talk to him. Alone.”

Tom considers it, closing his eyes and pressing his fingers to his temples as if he’s a clairvoyant trying to summon the future. “Fine,” he says. “I’ll give you five minutes.”

Mind made up, he grudgingly starts up the steps. At the halfway point, he turns to give me one last look of concern.

“I’m serious, Casey,” he says. “Don’t do a single thing she asks.”

I let that sink in as he clomps up the remaining steps. When he reaches the top, I hear the door close behind him and, unnervingly, the chain being slid back into place.

The only thing keeping me from panicking that I’m now also trapped down here is the person on the bed. At this moment, Katherine is enough to worry about.

“Why are you doing this, Katherine?”

“You know that’s not who I am.”

“It’s who you look like,” I say, although it’s no longer entirely true. Katherine’s appearance seems to subtly be changing, turning harder and colder. Like a layer of ice forming over still water.

“Looks can be deceiving.”

They can. I know that all too well. But I don’t for a second believe my dead husband is inhabiting Katherine’s body. Outside of it being completely beyond all laws of science and logic, there’s the simple fact that people’s brains are capable of strange things. They split and mutate and create all kinds of trouble. Katherine could have a brain tumor that’s causing her to act out of character, or she’s suffering from an undiagnosed multiple personality disorder that’s only now manifested itself. She knows who Len was. She knows what happened to him. After almost meeting the same fate he did, she might have convinced herself that she’s become him. All of that makes more sense than this possessed-by-a-spirit-in-the-lake bullshit.

Yet now that it’s just the two of us, I can’t shake the feeling that Len is somewhere in this basement. His presence fills the room just like it did when he was alive. Whether in our apartment or at the lake house, I always knew when he was around, even if he was out of sight in a distant room. I get that same sensation now.

But he can’t be here.

It’s just not possible.

“You need help,” I tell Katherine. “A hospital. Doctors. Medication.”

“That won’t do me any good.”

“It’s better than being held captive here.”

“About that, I agree.”

“Then let me help you, Katherine.”

“You need to start using my real name.”

I fold my arms across my chest and huff. “If you’re Len, tell me something only the two of us would know. Prove to me you’re really him.”

“You sure you want that, Cee?”

I gasp.

Cee was Len’s nickname for me. No one outside of close friends and family knew he called me that. Katherine certainly didn’t, unless I let it slip at some point. It’s possible I could have casually mentioned it when we were drinking coffee on the porch or chatting in the boat after I pulled her from the lake, although I have no memory of doing so.

“How do you know about that?”

“Because I came up with it, remember? I even used it the last time we talked, hoping you’d get the hint.”

My heart hopscotches in my chest as I think back to that late-night phone call and Katherine’s enigmatic wave from the window.

I’m fine. See.

Now I understand what she really said.

I’m fine, Cee.

But I also understand it was Katherine who said it. There’s no other person it could have been. Which means I had to have mentioned Len’s nickname at some point. Katherine remembered it and made it just another brick in her vast wall of delusion.

“That’s not enough,” I say. “I’ll need more proof than that.”

“How about this?” Katherine grins, the smile spreading like an oil slick across her face. “I haven’t forgotten that you killed me.”