A time bug traps Discovery in a loop through its own history, and Burnham must rally her crew to break it.
Moll plants a time bug, a weapon from the Temporal Wars, on Discovery, and when the ship reaches the next coordinates it begins jumping through moments in its own history. Burnham, Rayner and Stamets, whose unusual DNA protects him, are the only ones aware of the jumps.
They revisit the ship's construction, its fight with Control, its leap to the 32nd century, its capture by Osyraa, and a possible future in which the Breen use Progenitor technology to devastate the Federation. Burnham eventually lands weeks after she first came aboard, confronts her younger, mutinous self and wins the crew's help to break the loop. The delay gives Moll and L'ak a six-hour head start. Sean Cochran wrote the episode and Lee Rose directed.