Tom van Allen is a promising jazz musician and, above all, a happy man, revered by his young and beautiful wife, Liz. But his life changes the day she is murdered during a drug raid. To identify the culprits, Tom takes the name Danny Parker, infiltrates the drug world, and becomes an informant. Having quickly become addicted and brutally manipulated by police officers Garcetti and Morgan, the latter betrays the dealers he encounters along the way, with the sole exception of his faithful companion, the young and naive Jimmy The Finn. Thanks to him, Danny meets L'Ourson, a formidable drug dealer, with whom he closes a deal worth several hundred thousand dollars aimed at catching his wife's killers. But the ploy soon backfires...