Best of series, this 17th The Cat Who caper slyly creeps up on the reader. The newest delight in Moose County, ``400 miles north of everywhere,'' is a railroad buff's refurbished locomotive, which is making its debut run. Floyd Trevelyan, the train owner, disappears just as the state closes down the credit union associated with his business. While others believe the man has decamped with investors' money, newspaper columnist Jim Qwilleran doesn't believe Trevelyan would abandon his railroad project. He persuades his friend and sleuthing cohort Celia, recently moved to Pickax City from Chicago, to go undercover to find the missing businessman. Meanwhile, librarian Polly Duncan, with whom Qwill has had a long-standing relationship, is becoming distraught about the house she is building nearby. After a carpenter on the project is stabbed in a barroom brawl and the contractor, Trevelyan's son, is seriously injured on the job, Qwill begins to fear for Polly's health. Qwill's Siamese cat, Koko, plays a central role in solving these puzzles as Qwill struggles equally to interpret the cat's hints and cope with those problems complicating his personal life. Literary Guild, Mystery Guild and Doubleday Book Club selections. (Feb.)

Cat mystery lovers beware! Pickax's Qwilleran and Koko have returned for a go at catching a train fancier who has embezzled millions from Moose County investors. Another best seller from the prolific Braun.