Teenagers Vee (Emma Roberts, daughter of Eric) and Ian (Dave Franco, brother of James) find themselves caught up in the (possibly illegal) title app, a kind of “Truth or Dare” in which smartphone users elect to be “watchers” and pay a fee, or “Players” and get paid for completing dumb dares online. This is not great cinema; it could have gone way darker on the perils of instant fame through social media. But it’s unpredictable, moves along briskly, and never forgets that it’s telling a story. Call it a crayon-colored thriller for the wired teens of today. I had much more fun than I intended. (96 min)