The Way Back doesn't try to reinvent the prison-escape genre. Rather, director Peter Weir aims to illuminate moments of tenderness and tenacity among the desperate characters who walk across half of Asia toward freedom. Whether this story about fugitives from a Siberian gulag at the outset of World War II is based on fact is under debate. Regardless, it benefits from Weir's talent for big-canvas moviemaking, though the result is a commendable drama rather than a great one. As often happens, the film is stolen from its hero — Jim Sturgess as the liberal-thinking Pole who leads the group — by a sidekick: Ed Harris, as good as he's ever been, playing the embittered American expat "Mister Smith." After the escapees agree to let Polish teen Irena (Saoirse Ronan) join them, the bereft father and the girl gradually undergo a synchronization of souls. With lesser actors, the religious imagery accorded this relationship would be cheesy. Harris and Ronan make it a moving depiction of pure love.