Two of the most promising performers of their generation pair up with mixed results in Jesus' Son, New Zealand director Alison Maclean's loopy, intermittently brilliant adaptation of author Denis Johnson's cult novel. It's both an asset and a failing that McLean has kept as faithful as possible to her source material. Instead of being preachy or heavy-handed, the disjointed vignettes that tell the tale of junkie FH (Billy Crudup) and his erstwhile girlfriend Michelle (Samantha Morton) have a pleasantly unforced feel. Unfortunately, it's that same unforced rhythm that makes the movie evaporate from memory as soon as the lights come up. Along FH's journey to self-enlightenment, however, we're treated to a smattering of compelling moments: the shocking car accident that opens the film; the split-screen overdose of demented building contractor Wayne (Denis Leary, in an all-too-brief performance); and the surreal hospital job FH and his friend Georgie (the ubiquitous Jack Black) keep in order to score drugs -- any drugs. Our hero occasionally lapses into hallucinatory dream sequences which, at their best, recall Fellini; at their worst, they feel like warmed-over fantasy sequences from Ally McBeal. Through it all, the performances of the sensual, electric Morton and the laconic, dreamy Crudup -- in the first role perfectly suited to his sluggish charm -- keep the film from becoming a mere exercise in style.