The agents land near Area 51 in Nevada in 1955.

The Chronicoms meet with Sibyl, the Predictor of the Chronicoms. 

Area 51 is a S.H.I.E.L.D. base that experiments in space tech.

In 1955, there was a classified project called Helius that dealt with the creation of an ion fusion reactor that can be made into weapons. The agents think the Chronicoms are after it.

Yo-Yo tells Mack that her speed is malfunctioning.

They kidnap Gerald Sharp who works at the Department of Defense. Coulson steals his ID and Simmons uses Peggy Carter's to get into Area 51.

They start interrogating the people working on the Helius project to find out if any of them are Chronicoms.

Daniel Sousa, the old partner of Peggy Carter, shows up. He arrests Simmons and Coulson.

Daisy shows up in Sousa's office disguised as a CIA agent.

Deke finds out from the real Sharp that Helius cannot be powered from anything on Earth.

Deke believes that the Chronicoms can power it using themselves, creating a bomb that can take out many important S.H.I.E.L.D. agents.

May and Yo-Yo disguise themselves as pilots and infiltrate Area 51.

Sousa takes Daisy to see Coulson and Simmons. Coulson breaks from his handcuffs when May and Yo-Yo set off the alarms and locks Sousa in a holding cell.

May has a panic attack and Yo-Yo's speed fails her when they find the Chronicom.

Helius has been started up.

The Chronicom attaches herself to the machine.

May and Yo-Yo go to the machine and fight the Chronicom.

Another Chronicom shows up at the lab and Coulson fights him.

Simmoms and Daisy power up a device that emits an electromagnetic pulse that shuts down the Helius machine, the Chronicoms, and Coulson.

The Chronicoms self destruct.

Mack and Deke pretend to be aliens and drop Sharp in the middle of the desert to protect the timeline.