Discover how beavers are being recruited to reverse the effects of global warming on NATURE " Leave it to Beavers." Examine an ingenious plan to escape from a prisoner of war camp in Nazi Germany on NOVA "Escape from Nazi Alcatraz" and learn why all of Berlin was turned into a fortress during the final days of the Third Reich on NAZI MEGA WEAPONS "Fortress Berlin." Every Wednesday PBS shares the most exciting and inspiring stories that provide the answers that curious minds crave. Think Wednesday, Think PBS. Continues Wednesday May 14 at 8 PM.