In Source Code, Stevens asks Rutledge and Goodwin to let him die once the mission is complete.
Captain Colter Stevens is an injured soldier whose consciousness is connected to the Source Code system. The program repeatedly sends him into the final eight minutes before a train bombing so he can identify the terrorist responsible. Although the reconstructed scenario initially seems like a simulation, Stevens discovers that the system may generate alternate timelines.
Dr. Rutledge, who runs the project, initially promises to terminate Stevens after he completes the assignment. After Stevens identifies Derek Frost and helps prevent a second attack, Rutledge secretly breaks that promise because Stevens remains the only person able to enter the Source Code. Stevens therefore asks Goodwin to disconnect his life support, and Goodwin ultimately chooses to honor that request.
The ending adds an important complication. Goodwin sends Stevens back for one final attempt and disconnects him after eight minutes. In the resulting alternate reality, Stevens survives within a new timeline with Christina. Thus, “let him die” describes Stevens’s request and the original outcome outside the alternate timeline, rather than the movie’s final fate for every version of him.