This is the kind of role actors dream about. Depp plays an undercover FBI agent who infiltrates the mob through his friendship with a low-level mobster/big-shot wannabe (Al Pacino). It's a testament to Depp's talent that he holds his own on the screen with Pacino. It's a testament to his generosity as an actor that he helps Pacino deliver his best performance of the decade. Depp grounds this dark, twisted buddy tale with a passionate friendship that overshadows duty. His loyalty to Pacino's sad, insecure wise guy ultimately blurs the line between his lives on both sides of the law. Depp loses all perspective as he discovers his a knack for crime and slowly succumbs to the underworld pose he's been faking for so many years.