M*A*S*H è una tragicommedia incentrata sulle vicissitudini del 4077th Mobile Army Surgical Hospital (Ospedale Chirurgico da Campo dell'Esercito) statunitense in Uijeongbu, Corea, durante la Guerra di Corea (1950-1953).
Molte delle situazioni raccontate, anche le più assurde, sono realmente accadute, come testimoniano molti dei veterani del conflitto.
Frank throws his back out whilst spending the evening with Margaret, and ends up in traction. He promptly applies for the Purple Heart, having been 'technically' wounded at a frontline unit. Tommy Gillis, an old friend of Hawkeye's, is writing a book about the war, and pays him a visit. Later, Tommy is brought into the camp, seriously wounded, and Hawkeye can't save him. A 15-year-old kid is in the hospital to have his appendix out. He joined up to be a hero back home, but Hawkeye has him sent home, giving him Frank's purple heart.