D.O.A.
1950I want to report a murder
D.O.A. opens with its whole premise front-loaded: Frank Bigelow, poisoned with a slow-acting toxin he can't survive, spends the rest of the film investigating who killed him and why, racing a clock that's already run out. Edmond O'Brien plays the reveal completely straight, delivering "I want to report a murder... mine" without a wink, and the gambit worked well enough that the fatally-poisoned-man setup has been recycled by a stage musical, a 1969 West German remake, a 1988 Dennis Quaid version, and a 2022 reboot -- none of which needed permission, since the original fell into the public domain decades ago.