DIANE KRUGER and Bryan Cranston in “The Infiltrator.”

By Jim Tortolano

If you’re looking for a word to describe the work of actor Bryan Cranston, a good choice would be “authenticity.” Best-known as teacher-turned-drug lord Walter White in the HBO series “Breaking Bad,” he is the gold standard for craggy believability.

In the new film “The Infiltrator,” he’s back in the drug trade, but this time on the side of the angels. He portrays Robert Mazur in the based-on-a-true-story tale of how a federal undercover agent burrowed deep into a major narcotics cartel posing as a masterful money-launderer.

Mazur was assisted by a supersnitch (Emir Abreu) played impressively by John Leguizamo, who helps keep his partner from being discovered, a fate which would led to a grisly and disastrous end. Cranston convincingly navigates the demands of a role with two sides: dedicated operative and dedicated family man, interests that often are in conflict.

Diane Kruger’s role as Mazur’s phony fiancé (Kathy Ertz) gives the actress a chance to excel as well, moving her character convincingly from rookie agent to successful role player in a drama that, fortunately, has a satisfying conclusion.

Brad Furman directs the film in a taut, intimate style. It’s a bit talky and slow in spots, but you come away with a new admiration for the work of the folks who combat drug trafficking and the same old praise for the work of Bryan Cranston.

“The Infiltrator” is rated R for language, drug use, violence and some nudity and sexuality.