When we last left our idiots (Mick Rory's description of them) they were in Odessa, Texas in 1925.
The Waverider had been blasted to pieces by another waverider even though those were supposed to have been destroyed back in season 1.
Our band of idiots come up with a plan that of course failed. So in true Legends style they go through several other plans that go wong in different ways as they try to solve their problem and not ruin the timeline. End result they ruin the timeline with a major change that will have to be fixes this season.
All they need to do is make it to New York City to find the one mad scientist that can fix their main problem. Stay tune as they sea with historic figures.