The slashing starts early in “Logan”—no surprise, since it’s an R-rated action thriller about Wolverine, also known as Logan, the X-Men character with the tortured psyche and retractable claws.(He is played brilliantly by Hugh Jackman, who first played him 17 years ago.) The great surprise, which reveals itself gradually, lies in the depth and resonance of the drama. Yes, there is violence in abundance, sequences of spectacular mayhem that will thrill hardcore fans and scare off others. Yet this comic book epic, directed in masterly fashion by James Mangold, achieves a narrative grandeur that’s grounded in humanity, even though its superhero is a mutant.