DC's Legends of Tomorrow: Here's Your Fast-Forward Recap of "Knocked Down, Knocked Up"

Gwyn dies trying to save Alun at the fixed point, and we find out that human Gideon was responsible. This leads to a confrontation between the team and human Gideon. After she takes off angry, Spooner and Astra sneak aboard the Waverider to talk to her. We find out that Sara is pregnant because her alien DNA can do that just by kissing while THINKING about babies. Also the baby took her alien powers so she's human again. The team arrives a day early to save Alun so that they can first prevent Gwyn from dying. There, they figure out that without Sara's powers, they could get killed by whoever is manning the fixed point. They decide to try to reason with him, and leave a note for him to find.

Time freezes, and a man calling himself "Mikey" and wearing a hat that's blue with a yellow star strolls through the early morning battlefield, shanking golf balls through the trenches. He's the one manning the fixed point. 

He finds the team, unfreezes them to talk, they come to an agreement to save Alun by replacing him with a robot, who can then die, thus traumatizing younger Gwyn and ensuring that time travel is invented. But in doing this, he realizes that his Fixed Point is basically a joke, and that he was put there because whoever's in charge didn't believe in him.

Astra and Spooner get through to human Gideon, but Gideon AI has finally had enough of their shit and downloads herself into a highly-upgraded android body to hunt them down.  Human Gideon uses AI Gideon's rigidity against her: she is committed to eradicating all anomalies in the timeline, so Gideon shoots the part of the control console that activates the Waverider's camouflage. Suddenly it's visible to everyone on the war front, and AI Gideon reasons she has to destroy the Waverider

This should kill Gideon, Spooner, and Astra, but Astra manages to protect them with her magic, and then reassemble the Waverider around them. They land again, just in time for Mikey to steal the Waverider and then destroy Gwyn's time machine.

They manage to save Alun, although a mustard gas grenade corrodes all of Nate's steel away and leaves him powerless. Zari gives him her totem so that he can come and go as he pleases, rather than waiting for somebody to let him out. Nate leaves to go join Zari in the Totem, and just as they're trying to figure out how they're ever going to get home, Mikey shows up in the Waverider to save them Han Solo-style

Except no. There's jackbooted time cops on board, who arrest Mikey and all the Legends for crimes against time. And in case there was any doubt in your mind as to Mikey's identity, one of the time cops calls him "buster" in the scuffle and he corrects them that it's not Buster, but "Booster! I'm Booster Gold!"