He stood in the doorway of his anteroom and watched Mike and me walk back the short distance as though it were a gangplank. I opened the door and gave Mercer and Clem the word that someone had spotted her, and that Mamdouba was waiting to rap our knuckles and kick us out into the night.

Clem caught up with me as we walked toward the corner office. “Don’t blame yourself. I’m sure it’s my fault. I was getting a little frisky with those last e-mails. I’ll let you read them. I think I was too excited to exercise much caution. Zimm probably figured out I was already here. He may have thought he had to blow the whistle on me, for his own sake.”

The four of us took our places in the curator’s circular turret. Clem spoke first. “This is not the way I hoped to come back, Mr. Mamdouba. I think you know how much respect I have for this great museum, for the work of my colleagues, for-”

The bantam administrator wanted no explanations. He gave Clem a tongue-lashing for her unauthorized entry into the facility from which she had been banned months ago. I broke in to try to convince him that she had only come at my urging, at my direction. Mike jumped in to defend me, and only Mercer stood with calm reserve, behind Clem’s chair, his powerful hands on her tiny shoulders.

“This will mark the end of your comings and goings, Miss Cooper.” Mamdouba crushed the subpoena and threw it in the wastebasket.

“May I have a moment with you?” I motioned to the anteroom. I did not want to be discussing witnesses and evidence in front of Clem, but I wanted to impress upon the director of curatorial affairs the kind of access we needed from him and why we had taken the chance that we did. Traipsing through his displays in the daytime, with dozens of police officers in the midst of hundreds of schoolchildren, would be far less appealing than our clumsy efforts to operate more discreetly after dark. He also needed to know about our discovery in the basement, which we hadn’t disclosed to Clem.

I followed him out to the anteroom and closed the door behind us, for privacy. I made my pitch and explained how the search warrants would have to be executed, and what other requests I would make to the grand jury to compel his cooperation, but he had reached the end of his very short rope. The subpoena was only a piece of paper. He could rip it up and throw it away, but we still had the power to hold him in contempt.

“This is an institution of science, Miss Cooper. Make your case somewhere else. Go back to the Metropolitan. That’s where the dead girl worked, no? You have abused the privilege of being inside our walls, madam.” The little man was screaming now.

The door opened behind me and both Mike and Mercer joined us in the anteroom. Mike was ready for an argument while Mercer, as usual, took the diplomatic approach. He backed me away with a motion of his arm, and I took a seat on a nearby sofa to let him cool Mamdouba down.

“Ms. Cooper’s been known to step in shit from time to time. Maybe this wasn’t her brightest idea,” Mike said, “but we’re trying to solve a murder without shutting your doors to the public.”

“You’d have absolutely no reason to do that. No right. We won’t stand for it. You don’t even know where this girl died. All you have is a body somewhere in New Jersey.” He lowered himself into the chair at his assistant’s desk and wiped the sweat from the back of his neck.

“And a coat check from a cold day last December, right here in your lobby. And maybe enough arsenic to finish off every one of us. Let’s all be sensible,” Mercer said. “Why don’t we work out a schedule that meets with your approval. We’d like to keep you on our side, sir, okay?”

The two detectives outlined the way they wanted to proceed. Mamdouba was too agitated to listen closely. There would be no way to work out an agreement tonight.

“I’m sorry, Mr. Wallace. It’s very late, I’m quite tired, and I need to speak to the president herself before I can give you an answer.” He got up and walked to the door of his office, standing back as he pulled it open so we could go in and claim our trespassing Inuit.

I stood at the entrance and looked inside the perfectly round room. No one was there. Clementine Qisukqut had vanished.

Elijah Mamdouba brushed past me and strode to the center of his suite. He swept around and shook his fist at me. “Your fault, Miss Cooper. Enough games.”

I was dumbfounded. My heart was pounding and my head ached as if it were caught in a vise. It was as if two people were staring at a picture and seeing entirely different things: I knew something terrible had happened to Clem, while the director assumed she was the cause of the trouble.

Mercer raced in and started for the first of four doors that were set back into the walls of the room.

“Don’t touch that, Detective.” Again, Mamdouba was shouting at us. “She’s playing with all of us. You step into the tiger’s lair and you are surprised when the tiger bites you? We had no reason to trust Miss Clementine, and neither did you.”

It was as though her disappearance had relieved him of all the tension the evening’s events had created. He leaned forward, hands on his thighs, and broke into the heartiest of belly laughs.

Mercer opened the first door only to find an empty coat closet, wire hangers on hiatus until the chill of fall returned. He pulled at the next knob to reveal a small bathroom, toilet and sink.

Mike was livid. “What the hell are you laughing about? Where’s the girl?” He crossed the room and turned another handle. Pitch black. He stepped forward into the darkness and reemerged immediately. “Where are the lights?”

“She’s run away on you, Mr. Chapman. There’s the devil in that-”

Mike poked his head into the opening and yelled Clem’s name. “It’s a goddamn stairwell, Mercer. I can’t see a friggin‘ thing in there.”

He backed up around the large desk and bumped into Mamdouba, sticking him in the chest with his forefinger. “I don’t give a fat rat’s ass if Teddy Roosevelt falls off his horse and the animals come alive in their cages. Get every guard in this place on his feet, sound whatever kind of alarm you’ve got, get me a handful of flashlights, and tell me where the hell these stairs go. Coop, go back and get the floor plans. Hoof it.”

Mercer was on Mamdouba’s phone with the chief of detectives’ office. “Get Emergency Services here. Send me some patrol cars. Close off the streets around the museum… Theywhat? Don’t tellme they can’t. They do it to blow up Snoopy and those rubber cartoon characters for the Thanksgiving Day parade. Shut it down tighter than a crab’s ass. You got subway entrances north and south of the place. Block ‘em off.”

I ran back to our workroom and grabbed the maps off the top of the desk.

“What’s wrong with you, man? Why the hell didn’t you tell us there’s a secret staircase in there? You think Clem came over here from London to play games? Someone grabbed her right from under our noses. Use your brain.” Mike stormed back to the staircase. “What does this lead to and who had access to it?”

Mamdouba was in his fourth mood swing of the night. The displeasure that had turned to defiance and then briefly become hysteria had now sobered to misery. “It’s not a secret. There’s no reason for anyone to know about it. It’s, uh, it’s vestigial.”

“I left my thesaurus at the station house. Help me.”

Mamdouba had called the security command center and alarms were screeching overhead and echoing in the vast hallways beyond.

“Vestigial.Useless, like your appendix. Built a century ago, when these corner towers were constructed. They’ve been out of use ever since elevators were put in. The steps are narrow and dark and dangerous. Nobody uses them.”

Now Mercer was talking to the head of the hostage negotiation squad: “That’s the point. We don’t know who’s got her or where she is. It’s not premature. You damn well better have a team up here because if we find the girl and she’s alive, I’m gonna need all the help I can get. Pronto.”