Peter Weir’s The Way Back may be based on a supposedly true account that’s been mostly discredited, but that doesn’t make it any less fascinating. Did a group of prisoners really escape a Siberian gulag in 1940 and walk more than 4,000 miles to end up in India? Maybe not, but Weir’s version of the story is still gritty and compelling, if a little slow, with quietly commanding performances from Jim Sturgess as the group’s leader and Ed Harris as an indomitable American who inspires his companions to press on. Weir and cinematographer Russell Boyd effectively convey the grandeur and enormity of the landscape these men have to navigate, and the actors embody the desperation of such an extreme endeavor. The minor characters are a bit interchangeable, and Colin Farrell and Saoirse Ronan both disappear from the story without making much of an impact. But Weir is as unflagging as his characters, delivering an old-fashioned, unpretentious epic that reliably gets where it needs to go.