If the themes of Watch on the Rhine seemed timely when the Guthrie’s fall season was announced, they’ve only become more so in the succeeding months. Lillian Hellman’s political thriller premiered in 1941, just eight months before Pearl Harbor. Set near Washington, D.C., the plot concerns an American family hosting German relatives as well as another houseguest who’s secretly been conspiring with the Nazis. When it’s revealed that a man in the visiting family has been supporting underground anti-fascist operations, tension mounts as the Axis and Allies face off in a seemingly genteel American setting. Despite its heavy subject matter, this play has darkly comedic elements that make a strong moral argument: When freedom is at risk, there is no neutral ground. Regular theatergoers have been warmed up for this play with two shows last season: Park Square Theatre’s Idiot’s Delight, about Europe on the brink of war, and Prime Productions’ Little Wars, which imagined playwright Hellman and other remarkable women of the era convening for a 1940 meeting at the home of Gertrude Stein and Alice B. Toklas.