There are two movies rolled up into one in Red Letters. Like that great cliché about professional sports, it's a game of two halves: The first half of this engaging yet confounding film is a stirring erotic thriller that puts emphasis on the consequences of Professor Dennis Burke's affairs; the second half nosedives into a hare-brained farce that reaches its nadir in a scene in which an uncredited Pauly Shore is threatened on his bed by Burke (Peter Coyote) brandishing a pet snake. Don't ask. There is never a signal that the film, which creates a very tangible thriller mood in the early going, is going to devolve into low comedy involving ridiculous fright wigs and low-life bikers in the desert; the change of gears is abrupt and downright rude on the filmmakers' part as it ruins what appears to be a tasty finale of intrigue and sex. The film stays just barely afloat on the charisma of the leading man, Coyote, who works very hard at holding it all together. Nastassja Kinski and Fairuza Balk are wise to leave their performances off their resumes.