The most terrifying image on movie screens this year is the ice blue eyes of crime boss Jimmy “Whitey” Bulger, played by Johnny Depp in “Black Mass.” They are opaque, implacable, and piercing. Depp’s performance as the man who was second on the FBI’s Most Wanted List when Osama Bin Laden was number one is a return to form for one of Hollywood’s most talented performers, whose recent films have been a series of disappointments. His Bulger is coiled fury, horrifying when he kills, even more horrifying when gets an FBI official to tell him the secret recipe for a steak marinade and most horrifying of all when he strokes a woman’s face and touches her throat, pretending concern that she may be ill but very clear about the menace he is contemplating.

Director Scott Cooper (“Crazy Heart”) has assembled a superb cast to tell a complicated story. Bulger was a full-service crook — a killer, racketeer, extortionist, and drug dealer. When a businessman would not cooperate, he did not waste time making him an offer he couldn’t refuse. Told that he wouldn’t make a deal, he asks, “Will his widow make a deal?” And then the guy gets shot in the parking lot of his country club and she is a widow.

What makes this story different from the usual gangster film is that Bulger was enabled by a childhood friend from the neighborhood who became an FBI agent, John Connelly (Joel Edgerton). At first, they help each other, especially when Bulger tips off the FBI so they can go after his rivals, clearing the way for the expansion of Bulger’s Winter Hill gang into new territories and lines of illegal business. But the FBI ultimately becomes complicit, even turning over to Bulger the names of informants so he can execute them. “Black Mass” is a reference to a Satanic perversion of the Catholic rites of prayer, and this movie is about the secular perversion that has a murderer sharing a jolly Christmas dinner with the most powerful politician in the state (Bulger’s brother Billy, played with wily street smarts by Benedict Cumberbatch) and the FBI agent who is supposed to be investigating him.

Cooper and screenwriters Mark Mallouk and Jez Butterworth (based on the book by Boston Globe reporters Dick Lehr and Gerard O’Neill, keep the pressure taut. It opens on the close-up of one of Bulger’s Winter HIll gang, insisting he is not a rat, but making it clear is his about to tell the police what he knows. We can see every individual whisker on his cheeks, every bit of scar tissue from a lifetime spent getting beat up and beating up other people. (Extra credit to the makeup department headed by Joel Harlow for the most believable aging I’ve seen in a movie.) The score by Junkie XL is one of the best of the year, and the closing credit sequence is superbly designed.

We see Bulger harden over the years, as though he is freezing from the inside out. There is a lot of talk about loyalty but it is really about pride and power. Its exploration of the compromises that may be necessary to stop someone who operates entirely outside the rules and the implosion of spirit necessary to maintain those compromises gives a texture to the story by asking us to consider who was responsible for more damage and who was more responsible as well. Bulger is a deeply frightening bad guy. But the scarier bad guys are the ones who are supposed to be protecting us from the Bulgers of the world and protect them instead.

Parents should know that this movie is based on the true story of a notorious crime boss. It includes many brutal murders, drug dealing, racketeering, corrupt law enforcement, graphic and disturbing images, constant strong language, sexual references, prostitution, drugs, drinking, smoking.

Family discussion: What should the rules be for working with informants who are involved enough with crime to provide reliable testimony? Do you agree with the punishments for the various characters? What would you do differently?

If you like this, try: “The Departed” (Jack Nicholson’s character was in part inspired by Bulger) and “Goodfellas,” and the documentary “Whitey: United States of America v. James J. Bulger”