Tomorrow and Tomorrow and Tomorrow

A wounded man appears aboard the Enterprise, gives La'An a time travel device and dies. She finds herself in an alternate timeline where Earth is ravaged by war and James T. Kirk captains the Enterprise. The two travel back to the 21st century and land in present-day Toronto, searching for the moment history went wrong. As they work together, a romance grows between them. They discover that a Romulan agent, Sera, is trying to kill the young Khan Noonien-Singh, hoping to stop the Eugenics Wars and so prevent the Federation from ever forming. La'An faces a terrible choice but protects the boy who will become her infamous ancestor, and kills Sera. Her own timeline is restored, and an agent from the Department of Temporal Investigations collects the device. Later La'An contacts the real Kirk, who has no idea who she is. She keeps a watch as her only reminder of what happened.