Make every second count
Why it is hard sci-fi
A soldier is repeatedly inserted into the last eight minutes of a dead mans consciousness on a commuter train to identify a bomber. The film commits to a strict rule. The session is eight minutes, the body host is fixed, the source code is a quantum afterimage of the dead mans short-term memory rather than a time machine. The protagonist gets cleaner as a runner with iteration.
Science inside it
Quantum mechanical handwave called source code that captures eight minutes of post-mortem brain state. The film is honest that this is a fiction. What it gets right is the procedural shape of running a sensor that is not quite time travel. The team can only react to what their runner finds, and the runners status as a barely-living, paraplegic veteran is the cost.
Spoiler alert
The final run does not end the program. The runner stays in the source code after the bomber is caught and the train ride is replayed once more, this time without the bomb. The film argues that the source code creates a real branch of reality rather than a simulation, which contradicts the rules the team operated under, and is the films deliberate gamble.