The final of a trilogy
-- or is it the final?

''The Book of the Dead''
By Douglas Preston & Lincoln Child
(Warner Books, 454 pp., $25.95)
Buy at Amazon

Reviewed by John Orr
June 2006

''The Book of the Dead'' by Douglas Preston and Lincoln Child, is supposedly the final book in what they have called a trilogy that began with the fabulous thriller ''Brimstone'' in 2004 and continued with the almost-as-good ''Dance of Death'' in 2005.

The books all involve amazing crimes against persons, places and things but all end up revolving around the dangerous conflict between two unusual brothers: FBI agent Aloysius Pendergast (star of several Preston-Child novels) and his sociopathic brother Diogenes. In the first, Aloysius is apparently left for dead after being bricked into a castle dungeon; the second ends with Aloysius held in a modern prison; in both, Diogenes is left to run amok, and he does. The third, ''The Book of the Dead'' was supposedly going to wrap up the story of Diogenes.

''The next one will indeed finish the saga of Diogenes,'' Preston said in email to me in 2005.

But I just don't believe it. The ending leaves too much in question, and I think that Preston and Child (and their publishers and fans) are just having too much fun with the dynamic between the two brilliant brothers to end it now. More on that in a moment.

''The Book of the Dead'' begins with a mysterious box of brown dust being delivered to the New York Museum of Natural History. A huge post-Sept. 11 panic ensues but the crime techs announce it is just industrial diamond grit. Once it finally goes back to the museum, though, a curator discovers the truth:The brown dust is the smashed remnants of the museum's diamond collection, which Diogenes stole in ''Dance of Death.''

Desperate for some good news following that disaster, museum officials jump at the chance to open a long-closed exhibit, an ancient Egyptian tomb that was built into the very foundation of the old museum itself. It will be modernized with lights, sound, fog machines and an opening gala.

Well. Ancient (well-cursed) tomb, the Museum of Natural History, psychotic evil genius Diogenes running around -- and the brilliant engineer Eli Glinn and Sgt. Vincent D'Agosta trying to break Aloysius out of Herkmoor federal prison -- it all adds up to another wild ride from the Mr. Toad Brothers of popular fiction. Added to the tension elements this time: Diogenes' interest in Constance, Aloysius' mysterious ward who has only known the inside of a very old mansion for a very long time, although she looks very young; and the reappearance of Aloysius' apparent soul mate, Viola Maskelene.

It's all very deftly done, but we've seen it before. Despite all sorts of clever twists and turns, ''The Book of the Dead'' just doesn't have the scary edge of previous Pendergast tales by Preston and Child, such as ''The Cabinet of Curiosities,'' ''Still Life with Crows'' and ''Brimstone.''

And the ending? Well, it has too much in common with the ''death'' of Sherlock Holmes in one of Arthur Conan Doyle's stories. I just don't believe it.