Mara, a young creative writing professor, is struggling with problems in her marriage to an experimental musician. One day, Matt, a charismatic, free-spirited author from her past, wanders onto her university campus. Bonded by their shared interests, the two gradually become closer. When Mara’s husband unexpectedly cancels plans to drive her to an out-of-town conference, Matt accompanies Mara on the trip instead. Along the way, the tension surrounding their undefined relationship slowly grows.

The key to solving the toughest homicides lies somewhere in the final hours of a victim's life. In each one-hour episode, determined investigators must piece together events during this critical window to reconstruct the timeline, unlock the motive, and ultimately close in on the killer.