Kiera Cameron and the mysterious time traveler, Brad Tonkin must battle the Future Soldiers who arrived in a flash of light in the last moments of season three. Meanwhile, Kiera's alliance with the remaining members of Liber8 challenges her relationship with both Carlos and Alec Sadler. Kiera must also face off against Kellog, who is using every option available to him to become the ruler of a dark future built in his image.

Kiera Cameron's chance of getting home was hijacked when Alec Sadler, in hopes of saving Emily, the girl he loves, used the time travel device. This act of desperation not only jettisoned Alec into the near past, but it condemned Kiera to incarceration by the Freelancers, who are 'collecting' time travelers in order to protect history. Now, Kiera must face the consequences of Alec's betrayal and somehow escape the Freelancers. Even if she can, has Alec's decision to time travel already changed the future in ways Kiera couldn't even imagine? What will Kiera sacrifice to ultimately survive—and how will Liber8 factor into this challenge?

In search for answers, the highly anticipated sophomore season continues Kiera's uneasy alliance with Detective Carlos Fonnegra, and sees her grapple with the big question that closed the first season – why was she sent there? While Alec struggles to understand the implications of the mysterious message he received from his future self, the Liber8 terrorists become more strategic and even more lethal as they seek to ward off what they see as the seeds of a disastrous future.