Give it to would-be comedy caper "Mortdecai" for this: Johnny Depp (2014's "Into the Woods") commits fully to his bumbling, lunkheaded title character, an aristocratic art dealer with the eloquence (or lack thereof) of Inspector Clouseau. He and his central co-stars—Gwyneth Paltrow (2013's "Iron Man 3") as spitfire wife Johanna; Paul Bettany (2015's "The Avengers: Age of Ultron") as sexually voracious manservant Jock, and Ewan McGregor (2013's "August: Osage County") as the starry-eyed Inspector Alistair Martland—show no signs that they realize they are in a big-budget misfire of the first order. The globe-trotting plot finds the London-based Mortdecai agreeing to help Martland with his investigation into the murder of an art restorer and the theft of a valuable Goya, but really, the ins and outs of the story are inconsequential next to the movie's main focus: Mortdecai's ridiculous handlebar mustache.

Based on the 1973 novel "Don't Point That Thing at Me" by Kyril Bonfiglioli, "Mortdecai" is a tone-deaf head-scratcher with jokes so juvenile and pedestrian one has to wonder over and over how the picture got made at all. If director David Koepp's (2012's "Premium Rush") goal was to mount the next "Austin Powers," he has been sorely led astray by Eric Aronson's (2001's "On the Line") dismally bad screenplay, which seems to think Mortdecai's facial hair and Johanna's gag reflex every time she tries to kiss him are the height of hilarity. They are not, and as Mortdecai and Jock—and later Johanna—gallivant from London to Los Angeles, the supposed intrigue of their misadventures is undercut by one sad truth: there is nothing and no one on the screen to care about. "Mortdecai" wallows in the shallow and moronic as the energetic actors struggle to bring dignity to a project that has none. They should have known better.