After the defeat of the immortal villain Vandal Savage and the corrupt Time Masters who colluded with him, a new threat emerges. Dr. Nate Heywood (new series regular NICK ZANO), an unconventional and charming historian, is thrust into the action upon making a shocking discovery - the Legends of Tomorrow are scattered throughout time.

Nate must find a way to rescue the Waverider's beloved team of heroes and rogues, including Star City inventor Ray Palmer, who has created an exo-suit with the power to shrink him to minuscule size, as the Atom; Sara Lance, a trained assassin known as the White Canary; Professor Martin Stein and Jefferson "Jax" Jackson who together form the metahuman Firestorm; and career criminal Mick Rory, aka Heat Wave.

When the Legends encounter the Justice Society of America (precursor to DC's Justice League) in the 1940s, Amaya Jiwe, aka Vixen, joins the team. While the team reunites, a mystery looms - the fate of former captain Rip Hunter.

Once reunited, the Legends continue their new mission to protect the timeline from temporal aberrations - unusual changes to history that spawn potentially catastrophic consequences. When Heywood, the grandson of J.S.A. member Commander Steel, unexpectedly finds himself with powers, he must overcome his own insecurities and find the hero within himself.

Ultimately, the Legends will clash with foes both past and present, to save the world from a mysterious new threat.