“Now You See Me” starts with such energy and panache that it’s easy to imagine it becoming a classic. Alas, director Louis Leterrier (“Clash of the Titans,” “The Incredible Hulk”) allows the project to flag as it moves toward its final act. The picture’s flaws, most of which can be pinned on a weak twist ending, are frustrating, but primarily because the setup shows so much potential. 

When director Guy Ritchie (“Lock, Stock and Two Smoking Barrels,” “Snatch”) and actor Robert Downey Jr. updated the Sherlock Holmes mythos in 2009, they delivered an appealing blend of action, drama, mystery and suspense. Sadly, their return to the well is less appealing. That’s not to say “Sherlock Holmes: A Game of Shadows” is a disaster. Downey Jr. is still outstanding in the title role, most notably because he gives the master detective a sense of brutishness that isn’t typically seen in the character.