The team becomes stranded in 1925 after someone uses a future version of their time ship, the Waverider, to blow up their present ship, and the team must now find a way to get back to their own time.
The team needs to get to New York City as quickly as possible, so Sara and Ava come up with a daring plan: Nate, with Gary's help, will have to disguise himself as Hoover to carry out the mission.
Gideon, the AI who runs the timeship, has been transformed into a human, but she is infected with a mysterious virus that threatens her life. To save her from this danger, Astra and Spooner delve deep into Gideon's mind on a perilous journey.
The team is immersed in the world of organized crime in 1925 Chicago during a stopover in the city, and becomes embroiled in the local booze manufacturing and smuggling industry in the wake of Prohibition in the United States.
As the team prepares to use the time machine created by Dr. Davies, Sara and her team become excited to start their new adventure, but they are unaware of the dangers that are waiting for them.
The team loses track in a dense, uncharted forest after their timeship malfunctions, and decides to split up into pairs. Meanwhile, Behrad makes significant progress in locating them.
The team is forced to go to Seattle in 1940 in the midst of World War II, where they work in an aircraft factory alongside women who worked in factories during the war.
Sara begins to question her team's decisions to manipulate the course of time and realizes that their actions could lead to unforeseen, dire consequences. So she begins to evaluate everything she knows about the team and herself.
Gideon pilots the time ship, and the team finds themselves in the middle of a huge chaos caused by the crew of a reality show from the '90s. Meanwhile, Behrad turns to Nate and Zari for advice about Astra.
Sara decides that it is time to confront the Waverider instead of continuing to run from it, so she plans to create a massive time-lapse that will allow the team to take control of the evil ship and reclaim it.
Things take an unexpected turn when the team makes a fatal mistake, breaching a fixed point in time, which creates a hole that attracts the evil version of their ship, the Waverider.
The wicked Gideon continues to try to eliminate the team, and in an attempt to help them, their personal assistant negotiates a deal but breaks a basic rule. On the other hand, the team comes up with a new plan that may be the solution to all their problems.
After learning about Gary via her AI counterpart, Gideon is appalled. When the crew discovers that someone has violated the contract, Sara withholds risky information from Ava.