Tom Tykwer's new romantic triangle is a comedy with a genetic premise. One of its Berlin trio is a scientist who runs a gene-splicing company, where cell walls are routinely pierced and impregnated with new instruction sets. In this brave new world, 3 argues, biology is no longer destiny. Everything and everyone is mutable, and that includes the stale 20-year relationship between Simon and Hanna. Childless, unmarried, and infertile, they live in a bubble populated by fellow artists and intellectuals. New experiences are not to be expected until—enter the DNA probe—Hanna falls for enigmatic scientist Adam, who professes never to even read books. He lives alone in a sterile apartment, though his company profits from in-vitro fertilization for countless grateful couples. What comes next, as Hanna—astonished by her own actions—hooks up with Adam, and Simon suffers a health crisis, could've been treated as farce or tragedy. Fortunately, after a rather long, dull mid-career slump (Heaven, Perfume, The International), the German director of Run Lola Run has returned to form—using split-screens, voiceovers, and fantasy sequences to advance his hybrid story. It's full of weighty ideas yet wonderfully light on its feet. "Life is unpredictable," admits control-freak Hanna (the perpetually exasperated Sophie Rois). And so is 3—or so Tykwer would like us to believe. (Cynics will easily guess how determinism is to be toppled.) Is 3's thesis convincing? No. But is it warm, funny, compassionate, and entertaining? Definitely.