PERCHANCE TO DREAM: Robert B. Parker's Sequel to Raymond Chandler's The Big Sleep. Putnam, 271 pp., $19.95. IT'S ONE THING for a mystery writer to be compared favorably to the late Raymond Chandler, quite another to be Raymond Chandler. You don't have to believe in reincarnation to realize that Robert B. Parker, prolific author of the Spenser detective novels, has staked such a claim.

How so? First there was "Poodle Springs," Chandler's unfinished novel completed by Parker last year. Now there is "Perchance to Dream," Parker's sequel to Chandler's legendary 1939 novel, "The Big Sleep," made even more legendary by the movie starring Humphrey Bogart as Philip Marlowe.

After a prologue consisting of lengthy quotations from the conclusion of "The Big Sleep," Parker's sequel embarks on the next adventure. The time is indeterminate, apparently several years later. Gen. Sternwood has died, [Carmen] has been tucked away in a sanitarium and [Vivian Sternwood] is "still seeing" the gangster Eddie Mars. The Sternwood butler, Norris, summons Marlowe to the family mansion for an urgent mission. Carmen has disappeared. Can he find her?