THE NIGHT MONSTER. By James Swain. Ballantine Books. 336 pages. $26

OK, now let's see if you can keep this straight. There is an unincorporated town in Florida, with a population of 800, where more than a third of the citizens have mutilated themselves by severing one of their limbs for insurance money.

In fact, 200 of them collected nearly $20 million in a two-year period. The local sheriff has blackmailed them for 25 years and the town harbors two serial abductors who have not been arrested because they, in turn, are blackmailing the sheriff.

If you can buy that line, then you might enjoy "The Night Monster." The whole book is just as implausible as this ridiculous town -- an assault on our common sense.

Worse, the narrative moves from one juvenile fantasy to another. The central character, private investigator Jack Carpenter, knows (Believe me, he knows!) that when a family missing a child hires a particular lawyer, the child has not been abducted and the family member who hired him is guilty of child abuse.

Jack then proceeds glibly to unveil the subterfuge in an afternoon, rescuing the child, forcing the abuser to flee and humiliating the lawyer. It is all patently ridiculous.

Swain does establish a good narrative rhythm and the action is fast-paced.

You don't get through the book on willpower alone. You just have to adopt the mentality of a 12-year-old to stomach the improbable pap that holds this thing together.

-- Sam Darby practices law in Roanoke