After a string of less-than-stellar movies such as “Mortdecai” and “Transcendence,” the golden age of Johnny Depp had seemed to pass. But in “Black Mass,” Depp proves he actually has plenty of depth left in his acting.

Playing the Boston gangster, Whitey Bluger, Depp is terrifying. Scott Cooper, the film’s director, introduces Whitey by staring down one of his cronies while rummaging his fingers around a bowl of bar peanuts. There was something terrorizing in Depp’s eyes— like a snake observing its prey before striking.

The only vulnerability shown by Depp is when Whitey visits his son and girlfriend, played by Dakota Johnson. As he goes to see his son despite protests from his girlfriend that the kid’s already asleep, Depp’s character has a very human moment as Whitey watches his son sleep. Again, it’s Depp’s eyes that really sell his performance.

Johnson is 50 shades of yay in “Black Mass.” Even though she’s barely in the movie, Johnson stands out. The way her character hangs on Whitey’s every word with admiration is impressive, and Johnson completely sells it.

Benedict Cumberbatch, who plays Whitey’s younger brother and Massachusetts senator, and Kevin Bacon, an FBI chief, deliver their customary solid performances.

Juno Temple acts as a prostitute associated with Whitey’s Winter Hill Gang. It’s a minor role, but it’s interesting to note that this is Temple’s fourth prostitute role. One wonders if she likes playing ladies of the night or if she has been typecast. Hopefully it’s the former because Temple has a potentially bright future.

The plot of “Black Mass” is the film’s biggest miss— there’s no structure. It’s as if somebody just made a list of things that supposedly happened to Whitey and they acted it out. The decision to just recreate events in order instead of actually telling a story of how Whitey went from gangster to FBI informant to Kingpin of Boston is a disappointing, blown opportunity.

Thankfully, the strength of the supporting cast shoulders the plot’s dead weight and then some, propelling Depp back into acting’s upper-echelon where he’ll hopefully remain. But he did sign on for another “Pirates of the Caribbean,” so, fingers crossed.

Just as Whitey said “take you your best shot” to a drunk stooge who dared challenge him, Johnny Depp took his with Whitey Bluger and made a good, watchable movie.

George Johnston can be reached at [email protected] or @gjohnston786 on Twitter.