No good can come of this, I grimly mused, about 30 seconds into "Trenchcoat," which confirmed the hunch with a vengeance, proving one of the feeblest excuses for a comedy-mystery ever allowed to vacate movie theaters. Margot Kidder, evidently someone's misconception of an irrepressible comic heroine, had just outlined the premise over the soundtrack, confiding that her character, cutely yclept Mickey Raymond, was a court stenographer who aspired to be a mystery writer. Operating on the addled axiom that "to write a great novel you have to live a great novel," she was headed for a working holiday in Malta, where the atmosphere would surely drip with inspiring intrigue.

Given a mentality this dim, it's always difficult to decide whether the writers really want the protagonist to look idiotic right off the bat or simply can't compose in any key except the inane. A new team, Jeffrey Price and Peter Seaman, is responsible for the sluggish brew of deceptions, misconceptions, abductions, romantic spats and runarounds that constitute the "scenario" of "Trenchcoat," which may still linger at the stray area theater, so perhaps they're merely getting a bum idea out of their systems at the start of glittering careers. At the moment, unfortunately, their wit, verbal and otherwise, can be accurately gauged by a line entrusted to the heroine when she feels vexed with a police official: "If you looked up 'stupid' in the dictionary, you'd find his picture!" It is not to laugh, certainly; maybe it is to choke.

Malta, which might seem an interesting out-of-the-way locale on most occasions, barely looks presentable through the BleachoColor in which "Trenchcoat" seems to have been processed, no doubt wedged in by the lab between regular work printing snapshots for the drug chains. Speaking of drugs, the plot is contrived to thicken when Kidder blunders into an apparent drug-smuggling conspiracy, ultimately revealed to be a trifle more explosive than hinted. She also has her most animated and endearing moments when pretending to be limp and drowsy (not unlike the audience, curiously enough) from an injection of sodium pentothal.

A few performers manage to sustain an almost heroic professionalism and lightness despite the stupefying drabness and clumsiness that distinguish director Michael Tuchner's "light touch." As the romantic costar, a government sleuth posing as a skirt-chasing trinket salesman, Robert Hays once again demonstrates his natural superiority to Chevy Chase at projecting a slightly apologetic, callow charm. David Suchet and Daniel Faraldo contribute smooth performances as an unflappable police inspector and devious gigolo, respectively, and Ronald Lacey, who did a brilliant comic grotesque as the piggy SS agent in "Raiders of the Lost Ark," adds his name to the growing list of expert cross-dressers with a cunningly effective cameo as "Princess Aida," the headliner at a Maltese cabaret.

Still groping, the Disney organization bankrolled "Trenchcoat." It has to be all uphill from this point, because "Trenchcoat" is indisputably the farcical pits.