Our movie critic's picks of the week

Slingshot PhilaMOCA, 531 N. 12th St., 4:30 and 7:30 p.m. Sunday. The festival-winning documentary about engineer and inventor Dean Kamen (the Segway, the iBOT Wheelchair, AutoSyringe) and his decades-long mission to design and distribute a water-purification machine, turning fetid H2O into potable fluid, therein eliminating a huge source of human illness. "Throughout my life I only start on projects, typically, if enough credible people tell me, 'You're nuts,' " the lively, funny Kamen says in the film. "Because then you know this must be a big problem." Info: 267-519-9651. Tickets: www.slingshotdoc.com/screenings/

The Godfather: Part II Ambler Theater, 108 E. Butler Ave., Ambler, Thursday. "There are many things my father taught me here in this room," says Al Pacino as reluctant crime family scion Michael Corleone. "He taught me keep your friends close, but your enemies closer." Francis Ford Coppola's epic sequel offers not only a dark take on the American Dream, but some of the greatest movie making - and movie performances - of the 1970s. Winner of best picture, best director, and four more Oscars (Pacino was nominated but lost the best actor nod to Art Carney for Harry and Tonto; Jack Nicholson was also a nominee for Chinatown). Part of the Ambler's "Hollywood Summer Nights" series. www.amblertheater.org/

The Martian Andy Weir Broadway Books, 387 pp., $15. One of the biggest self-publishing success stories out there, Weir's sci-fi survival tale has sold millions of copies - at least one copy of which belongs to Ridley Scott, who has turned it into one of the most hotly anticipated films of the fall. Matt Damon stars as an astronaut left for dead on the Red Planet, and the NASA crew that left him there - including Jessica Chastain, Michael Peña, and Kate Mara - is determined to go back and get him. So what if it takes four years and their bosses have said no? Read the book before The Martian opens in November.