It stuck for my first few attempts, then opened wide as I yanked again, practically dislodging me from my perch. Bea reached out to steady my legs.

The thick layer of dust that coated the interior shelf had recently been disturbed. Streaks across the width of the space suggested someone had reached inside.

“You might be right, Bea,” I said.

“Hey, Mike,” she called out. “Come help us.”

Mercer and Mike were behind me seconds later.

“Make yourself useful, Bea,” Mike said. “I’ll hold her legs.”

He put his hands around my calves, squeezing them to reassure me that all was okay between us.

I reached back and ruffled his thick black hair.

Mercer opened several closet doors until he found a stepladder. He helped me down and, with his great height added to the three steps, was halfway inside the cabinet when he called out, “There’s a false front here.”

He leaned to the side, pulling out the piece of wood that formed the crossbar for the single shelf.

In the space behind the center cabinet-a good four feet wide-was the side of the metal chamber we had seen from above.

Directly in front of Mercer, in the seam of the concealed door, was a keyhole-an old-fashioned design, which looked like it would accommodate a notched tip turned with an ornate bow.

“Call the lab, Mike,” I said. “Get someone up here with the key that I found in the library stacks.”

“It’s a fake,” Bea Dutton said, her gloved hands spreading the parchment that appeared to be a panel of the 1507 world map across one end of my dining room table, after we’d made the short drive from East Ninety-third Street.

We had waited forty minutes in the basement apartment until one of the forensic biology lab techs appeared with the key that I had found along the path the killer probably took to dispose of the body of Tina Barr.

Mercer had opened the locked chamber to reveal a watertight series of metal chests within chests-like a small version of the caskets in Napoleon’s tomb-and removed them from the hidden compartment.

The smallest one was fitted with a velvet lining large enough to hold double-folio-size prints. Only one thing-a piece of the map-rested within the case. Mercer removed it and Mike called the lieutenant to tell him we were on our way to my apartment to determine what it was.

“How can you tell it’s a fake?” I asked.

“Remember what I said yesterday about forgeries of something as detailed as this piece? The fact that it’s a made from a woodcut, not just a drawing?” Bea asked. “It would be next to impossible to pull off.”

Bea put on her reading glasses and began to examine the paper more closely.

Mike was looking over her shoulder. “Which of the twelve parts is it?”

“Winturn Eurus. The easterly skies. That’s the coast of India, with Tibet above it, and the island of Java off to the side. It’s one of the easier panels to try to copy because so much of it is just water rather than the finely documented landmasses, which require minuscule writing and exquisite particularity.”

Bea rubbed the edge of the parchment between her fingers. “The texture is the first giveaway,” she said, starting to explain the flaws. “Most experts could tell right off the bat.”

“Someone like me, Bea, who doesn’t know rare maps,” I said. “Would it fool me?”

“Stevie Wonder could tell this one’s a forgery, Coop. Get with the program.” Mike pulled at a strand of hair that had fallen between my eyes. “Make yourself comfortable, Bea. Want a soda?”

He walked into the kitchen and helped himself to a soft drink.

“Nothing, thanks. Do you have that photocopy of the entire map I made for you at the library?”

“I got it,” Mercer said. He had brought a stack of work up from the car and sorted it out from the pile he had dropped on the credenza on his way inside.

“Let’s lay it out on the table. Do you mind if I move your flowers, Alex?” Bea asked.

Mike lifted the vase of white lilies. “More where those came from, Bea. Guess this guy didn’t get so lucky. The place usually looks like a funeral home when she’s put out her best stuff.”

Bea ignored him. “Grab me some tape and a few pads.”

Mike knew his way around my place. He left the room, then returned from my office with what Bea requested.

“You guys keep going on your end. Let me play with the map a bit,” she said.

Mercer, Mike, and I set ourselves up around the coffee table in the living room. It was late in the afternoon, and the three of us were trying to use a quiet Saturday to regain the territory and figure out what we had to work with so far in the murders of Tina Barr and Karla Vastasi.

“You liked what the old broad had?” Mike asked.

“Jane Eliot?” I said. “Absolutely.”

“But the guy who broke in to her place didn’t bother with a mask. So why would he bother with the fireman outfit the first time he hit Tina Barr’s place?”

I leaned back and put my feet up on the sofa. “Maybe he thought she’d make him, recognize him.”

Mercer nodded. “Possible. Didn’t mean to kill her if he could find what he was looking for in the apartment.”

“Jane Eliot can’t see well enough to describe her assailant,” I said. “If he knew her vision was impaired and was confident she had no reason to identify him from any previous encounter, he didn’t have to go to the trouble of hiding his face. Besides that, he’d lost the gas mask.”

“Alex has a point,” Mercer said. “The delivery uniform he wore to break in to Eliot’s was a disguise of sorts.”

Mike had found a deck of cards in the drawer of the coffee table and was playing solitaire while we talked.

“Did you ever follow up with the lab on that DNA profile in the mask?” I asked Mike.

“I’m on it. Partial match to Billy Schultz, but it’s a combo, so they can compare it to other samples we submit.”

“So how you doing on profiles?” Mercer asked. “Whose DNA have we got?”

“Schultz’s, obviously. But his alibi works for Tina’s murder,” Mike said. “And I gave the lab the Hunts.”

“Which Hunts?” I asked.

“Let’s see,” he said, folding his losing hand and shuffling again. “Minerva’s first.”

“I know they’re only amendments,” I said, too tired to go at Mike full force. “But they are still part of the Constitution. Hope the seizures were lawful, but then if they were, I probably would have known about them.”

“That cigarette butt she crushed to death in the squad room the other night? Abandoned property,” Mike said.

“I’ll give you that,” I said with a smile. “Nice work.”

“Think of it, a woman inside a fireman’s uniform and mask. Who’d guess that? You automatically assume it’s a guy.”

Bea Dutton looked over at us every now and then as we tried to put the clues together.

“You’re right, Mike. It would never occur to me, hearing that description, to think of a Minerva Hunt-or a Jill Gibson.”

“What are you saying about Jill?” Mike asked.

“Forget I mentioned it. It’s just a personal thing.”

“I’m gonna talk to you about that, Bea,” Mike said. “You can’t hold back if you think there’s something that might be useful to us.”

“Sorry. I just think she plays both sides of the street. She means well, but she’s in a difficult position, as an administrator, between sucking up to the board and keeping her staff squared away.”

I made a note on the top of my pad to get back to Bea Dutton.

“So what did you get from Talbot Hunt?” I asked.

“Swiped a cocktail napkin that the butler missed in the living room yesterday. Figured the one with lipstick was Minerva’s and the one without was her brother’s.”

“Swiped doesn’t work for me.”

“Don’t get in a swivet about it, Coop. I didn’t take it from his house. He doesn’t have any standing at Papa’s pad. Give me any illegal search bullshit and I’ll have a seizure.”