She lowered her chin and peered at me over the tops of her half glasses.

“No, you didn’t, did you? I should like to know, before I go any farther.”

“The original owner, who was also probably the artist responsible, is dead. He was a Mexican named Garcia. Neddo believed that he was also behind the restoration of an ossuary in Juarez, and the creation of a shrine to a Mexican figurehead called Santa Muerte.”

“How did the late Mr. Garcia meet his end?”

“You don’t read the papers?”

“Not if I can help it.”

“He was shot.”

“Most unfortunate. He appeared to have considerable talent, if he made this. It really is very beautiful. My guess is that the human bones used are not old. I see little evidence of wear. The majority are from children, probably chosen for reasons of scale. There are also some canine and avian bones, and the nails on the ends of its limbs appear to be cat claws. It’s most remarkable, but probably unsalable. Questions would be asked about the provenance of the child bones. There is the strong possibility that they may be linked to the commission of a crime. Anyone trying either to buy or sell it without involving the authorities would leave him- or herself open to charges of obstructing the course of justice, at the very least.”

“I wasn’t trying to sell it. The man who made this was involved in the killing of at least two young women in the United States, and perhaps many more in Mexico. Someone arranged for him to come north to New York. I want to find out who that might have been.”

“So where does the statue fit in, and why bring it to me?”

“I thought it might pique your interest and allow me to ask you some questions.”

“Which it did.”

“I’ve been holding one question back: What can you tell me about the Believers?”

Ms. Stern killed the light. The gesture allowed her a moment to compose her features and to hide partially the expression of alarm that briefly transformed them.

“I’m not sure that I understand.”

“I found a symbol carved inside a skull in Garcia’s apartment. It was a grapnel. According to Neddo, it’s used by a group of some kind, a cult, to identify its members and to mark some of its victims. The Believers have an interest in the history of Sedlec and in the recovery of the original statue of the Black Angel, assuming it even exists. You’re about to auction off a fragment of a vellum map that is supposed to contain clues to the location of the statue. I would imagine that would be enough to attract the attention of these people.”

I thought Ms. Stern was going to spit on the ground, so obvious was her distaste at the subject I had raised.

“The Believers, as they term themselves, are freaks. As I’m sure Mr. Neddo informed you, we sometimes deal with strange individuals in the course of our work, but most of them are harmless. They are collectors and can be forgiven their enthusiasms, as they would never hurt another human being. The Believers are another matter. If the rumors are to be credited, and they are only rumors, they have existed for centuries, and their formation was a direct result of the confrontation in Bohemia between Erdric and Immael. Their numbers are small, and they keep a very low profile. The sole reason for their existence is to reunite the Black Angels.”

“Angels? Neddo only told me about one statue.”

“Not a statue,” said Ms Stern, “but a being.”

She led me to where the man with receding hair was working upon the restoration of the painting. It was a large canvas, about ten feet by eight, and depicted a battleground. Fires burned on distant hills, and great armies moved through ruined houses and scorched fields. The detail was intricate, each figure beautifully and carefully painted, although it was difficult to tell if what I was seeing was the battle itself or its aftermath. There appeared to be pockets of fighting continuing in sections of the painting, but most of the central area consisted of courtiers surrounding a regal figure. Some distance from him, a one-eyed leader rallied troops to himself.

The work had been placed upon an easel and surrounded by lights, almost like a patient in an operating theater. Upon the shelves around it stood microscopes, lenses, scalpels, magnifying glasses, and jars of assorted chemicals. While I watched, the restorer took a thin wooden stick and scored it with a penknife, then pushed it into cotton and rotated it to create a cotton bud of the required thickness. When he was satisfied with his creation, he dipped it into a jar of liquid and began carefully applying it to the surface of the painting.

“That’s acetone mixed with white spirit,” said Ms. Stern. “It’s used to clean away unwanted layers of varnish, tobacco, and fire smoke, the effects of pollution and oxidation. One has to be careful to find the correct chemical balance for every painting, because the requirements of each one will be quite unique. The intention is to achieve a strength sufficient to remove dirt and varnish, even paint added by later artists or restorers, without burning through to the original layers beneath. This has been, and continues to be, a particularly painstaking restoration, as the anonymous artist used an interesting mixture of techniques.”

She pointed to two or three areas in the work where the paint appeared exceptionally thick.

“Here, he has used oil-free paints, giving his pigment an unusual consistency, as you can see. The impasto-the thicker areas of paint-have accumulated layers of dust in the grooves, which we’ve had to remove with a combination of acetone and scalpel work.”

Again her hands danced across the work, almost but not quite touching the surface.

“There is also a great deal of craquelure, this web effect where the old pigments have dried and degraded over time. Now, let me show you something.”

She found a smaller painting, depicting a solemn-looking man in ermine and a black hat. Across the room, her secretary abandoned her work and moved over to join us. Apparently, Claudia Stern’s master classes were worth attending.

“In case you were wondering, this is the alchemist Dr. Dee,” she explained. “We are due to offer this for sale at our auction, alongside the painting upon which James is currently working. Now, let me adjust the lighting.”

She turned off the large lights surrounding the paintings, using a central switch. For a moment we were in semidarkness, until our corner of the room was suddenly illuminated by an ultraviolet glow. Our teeth and eyes now shone purple, but the greatest change was visible upon the two paintings. The smaller work, the depiction of the alchemist Dee, was spattered with specks and dots, as though the entire work had been attacked by a demented student of Jackson Pollock. The larger painting, though, was almost entirely clear of such marks, apart from a thin half-moon in one corner where the restorer was still working.

“The dots on the portrait of Dee are called ‘overpaint,’ and they show the parts where previous restorers have retouched or filled in damaged areas,” said Miss Stern. “If one were to perform the same experiment in almost any great gallery in the world, one would witness the same effect on most of the works present. The preservation of works of art is a constant process, and it has always been so.”

Miss Stern lit the main lights once again.

“Do you know what a ‘sleeper’ is, Mr. Parker? In our business, it is an object whose value is unrecognized by an auction house, and that subsequently passes into the hands of a buyer who realizes its true nature. This battlefield painting is just such a sleeper: it was discovered in a provincial auction house in Somerset, England, and bought for the equivalent of one thousand dollars. It’s clear that the sleeper has not been restored at any point in its existence, although it appears to have been kept in relatively good condition, apart from the inevitable effects of natural aging. Yet there was one large area of concealment in the bottom right-hand corner, noticeable once the overpaint was revealed by the ultraviolet light. Originally, sections of this work had been crudely worked upon to conceal some of the detail it contained. It was uncovered relatively easily. What you are seeing here is the second stage of the restoration. Take a step back and look at that area with a new eye.”