WHAT PLANET is Emily Watson from? Elfin-looking, yet surprisingly tall, with a broad open face where sparkles dwell, Watson's eyes smile but communicate nothing. She seems to be attuned to an inner music to which no one else is privy. Directors tend to use her when they want a woman-child, a naîf lost in a hard-luck world.

From her first film, Breaking the Waves, in which she was the fanatical sex slave of her lusty husband, to Hilary and Jackie, where her drive to master her instrument and her career left little room for others to care for her, she has been elevated to oddity. Watson is in grave danger of devolving into another Amanda Plummer, a wacko who doesn't connect with audiences.

In Trixie, director Alan Rudolph uses the mutant side of Watson at the expense of her human side, which rarely surfaces. We've seen it in Metroland, where she has the thankless task of playing the disapproving wife, and in The Cradle Will Rock, but these are rare exceptions in a short career. Trixie wants Watson to be the primary Watson, the ethereal waif seemingly without an anchor in the world. Trixie's signature trait is a non-stop string of malapropisms, such as "You've got to grab the bull by the tail and look it in the eye." Her mangled metaphors make a sort of sense, but after 40 of them in the first half hour, they wear out their welcome. Trixie is no Yogi Berra, where wisdom lurked within the surface contradictions.

But Trixie fools everyone, including the viewer. Chicago-bred, she is a girl who wanted to grow up and be a detective. Instead, she took a wrong turn and ended up as a security guard. Assigned to work a casino in the Northwest, she is soon embroiled in a case involving the death of a crooked land developer's mistress (Lesley Ann Warren).

She has some urgency in solving the case because the virginal, almost asexual, almost ahuman Trixie seems to have fallen for the town's resident Dex Lang (Dermot Mulroney), whom the police view as a person of interest in the case. Trixie is really a whodunit tricked up to be a comedy (Rudolph calls it a "slapstick noir"). Nick Nolte and Nathan Lane are along for the ride, assigned the sole task of being suspects, and invited to overact to alleviate their boredom. In the end, it turns out that everyone has underestimated Trixie, who is sharp, alert, and competent, and solves the crime when all others were chasing rainbows.

Trixie is a weird movie, definitely not to everyone's taste. Rudolph has long been under the dire sway of Robert Altman, his mentor (and the executive producer of this film). Yet they are grossly dissimilar (do they even know this about each other?). While the dyspeptic Altman hates everyone and everything, Rudolph has a sneaking fondness for love stories, a genre he returns to obsessively, from Choose Me to Afterglow. He takes them seriously and wants them to have happy endings. His addiction to love stories seems to blind him to how his actors appear to be in different movies.

Yet Watson manages to anchor the movie and charm the sympathetic viewer, and if you can look past the Altman-esque chaos, the murder mystery isn't half bad. At least, Planet Watson is a nice place to visit.