A biopic about an undercover federal crime fighter can go two ways. It can delve deep and journalistically into the procedural details of the job, à la "The Wire." Or it can focus on the excitement of impersonating a bad guy, emulating the hedonistic exuberance of Goodfellas. In this adaptation of Robert Mazur's book, director Brad Furman (The Lincoln Lawyer) doesn't fully commit to either strategy. The result is a film full of splashy set pieces that never build to anything interesting.

The biggest problem is the unfocused figure at the center of the film. The story of Mazur (Bryan Cranston) is full of dramatic potential: In the 1980s, working for U.S. Customs in Tampa, Fla., he played a key role in a landmark takedown of the Medellín cartel's money-laundering operation. Playing the role of corrupt, mob-connected businessman "Bob Musella," Mazur lived the high life, fêting drug dealers at a borrowed mansion and even showing off a "fiancée" (Diane Kruger) who was a fellow undercover agent. In theory, his is a story that allows the audience to enjoy both the thrill of ill-gotten gains and the satisfaction of seeing the bad guys put in cuffs.

But did Mazur himself enjoy any of this? The screenplay by Ellen Brown Furman puts him front and center yet keeps his motives frustratingly vague. Clearly we're meant to deduce them from a scene in which Mazur gets schooled by his acerbic Aunt Vicky (Olympia Dukakis). She represents his forebears, some of whom were themselves criminals. But it's not clear why her lecture on family honor inspires Mazur to cling to his dangerous, unlucrative job, especially when his own family begins to suffer as a result of the double life he's leading.

No doubt Cranston seemed like a natural choice because of his role on "Breaking Bad," where he likewise split his time between suburbia and squalor. But Walter White had clear goals and a tragic flaw: He liked being bad. Here, Cranston pulls out all his familiar twitches and tics, hinting at shadiness and ambivalence, yet we're never given concrete reason to doubt that Mazur is anything but a standup guy doing his job.

To compensate for this static protagonist, Furman stuffs the film with flamboyant supporting characters. From Mazur's hothead partner (John Leguizamo) to a white-suited, sexually aggressive gay Medellín operative (Yul Vazquez), many of the people on-screen seem to have stories more compelling than the one we're watching.

Feeling long at slightly over two hours, The Infiltrator is a patchwork of elements that tantalize us without satisfying. Twice in the film, Mazur's operation is saved from certain discovery by sheer luck — a pattern that, whether or not it reflects true events, makes his character seem passive and the audience feel manipulated. Without a strong sense of cause and effect, the plot becomes just a bunch of stuff happening.

There are would-be operatic scenes of decadence (often set to painfully on-the-nose songs); there are long tracking shots; there are period fashions galore; there are fitful hints of the ultimate futility of Reagan's war on drugs. But the film is neither enlightening enough to rivet us nor suspenseful enough to make us care about its elaborate finale. Imagine American Hustle without the (somewhat) saving grace of silliness, and you have a period piece that won't send anyone out on a high.