Tartu--or more formally, The Adventures of Tartu--stars
Robert Donat as a Rumanian-born British spy, dispatched to Czechoslovakia during World War II. Posing as an ineffectual milquetoast, Donat is hired as a chemist in a Nazi-controlled poison gas factory. Working in concert with the Underground, our hero spends his off-hours dismantling the Nazi operation. Then he has to figure a way to get out of Czechoslovakia as adroitly as he got in.
Adventures of Tartu was filmed at MGM's British studios (it was Metro's first British production in two years), with an American director but with a full cadre of English acting talent: Donat,
Valerie Hobson,
Glynis Johns, etc. The Teutonic villain is played by Walter Rilla, whose son Wolf Rilla later became a prominent British director. ~ Hal Erickson, All Movie Guide