“The Informer” (*** out of four) was an engrossing melodrama about a former criminal turned undercover informant (Joel Kinnaman) who has to go into federal prison on a last assignment but doesn’t realize the federal agents he’s working for (Clive Owen and Rosamund Pike) have an agenda of their own and he is caught up in a much larger conspiracy and operation than he realizes. Plenty of twists and turns in this familiar but entertaining story. Owen is aces in a role he can probably play in his sleep by now, Common is strong in his umpteenth role as a hard-boiled cop, and Kinnaman carries the movie in probably his best performance yet. A small gem all around