The awesome Robert Downey Jr. is to lead the Ben Stiller directed comedy Tropic Thunder. Stiller's three previous movies that he has helmed include Reality Bites, The Cable Guy and Zoolander. Plot of Tropic Thunder from Coming Soon.... In the film, everything goes wrong during the making of a big-budget war movie, and the actors end up becoming the commandos they are playing. Downey will play Kirk Lazarus, the greatest actor of his generation and a four-time Oscar winner. Jay Baruchel has also signed on the flick. Justin Theroux who co-wrote the script of the movie with Stiller and Idiocracy scribe Etan Cohen has been attached to star in the film from day one. No doubt this will be as dumb as the usual Ben Stiller flick but well at least Downey Jr. will be worth watching. source - coming soon, the hollywood reporter