An unassuming divorced English teacher stumbles upon a time portal that leads to 9th September 1958, and goes on a quest to try and prevent the assassination of John F. Kennedy.

Thrown by the enormity of his goal, Jake decides the one thing he can do to make a real difference is to save the family of his friend Harry Dunning (series regular Leon Rippy), whose family was murdered in a small Kentucky town by Harry's out-of-control father, Frank (series star Josh Duhamel). But does Jake have what it takes to kill a man? And what are the consequences of violence — even against someone as dangerous as Frank?

Jake finds an unlikely ally in his quest in local drifter Bill Turcotte (series star George MacKay). He gets a teaching job in a small town near Dallas and discovers romantic sparks with a school librarian Sadie Dunhill (series star Sarah Gadon). Meanwhile, Jake constructs a double life – spying on Lee Harvey Oswald (series star Daniel Webber) at night, as the potential assassin within Jake builds. Trailing Oswald takes Jake into the dark side of Dallas where he realizes Oswald may not be the only threat Kennedy will have to face.

Jake and Bill's partnership shows signs of strain as they discover more secrets surrounding the unpredictable Lee Harvey Oswald. While romance blossoms for Jake and Sadie, the conspiracy deepens involving Oswald. But by becoming involved with an innocent bystander, has Jake placed his new love in danger?

Everything begins to fall apart as Jake struggles to live two lives – as teacher and time traveler. When Sadie's life is threatened, Jake has to make a terrible choice, leaving Bill to his own devices. Meanwhile, Lee Harvey Oswald takes steps that will lead him toward his date with destiny.

It's October 1963, and the gathering storm of threats in Dallas continues to build. While Jake must take drastic action to establish the full dimensions of the threat to Kennedy, he's hit with an unexpected death and a bitter betrayal from one of those closest to him.