This soft-boiled sub-Spielbergian mush is a children's film for grown-ups who never grew up. In a scurrilous bid to muscle in on Robin Williams' territory, Spacey plays social studies teacher Eugene Simonet, a virgin with bad skin and a preposterous vocabulary. Mr Simonet sets a class project: to think of an idea to change our world and act on it. Lonely, serious Trevor (Osment) comes up with an inspired wheeze. He brings home a tramp (Caviezel), gives him a place to stay for the night, and sets him straight on a few things. Don't return the favour to me, he tells him, pay it forward to three strangers, and tell each to do the same. Only a hardcore cynic would diss such an altruistic daydream but somewhere along the line the message gets scrambled. A singularly ill-judged, suspense-crushing subplot has reporter Mohr tracing the phenomenon from its tentacles in Chicago, where one man has given a perfect stranger his Jaguar. The script's relatively realist Las Vegas milieu is ill-served by director Leder's sentimental overkill, while Spacey and Hunt (as Trevor's alcoholic waitress mom) make heavy weather of being normal. (From the novel by Catherine Ryan Hyde.) TCh.