Plot summary
Carter decrypts an encoded message, received from Leviathan through Demidov's typewriter, for the SSR, learning that Stark will be selling weapons to Leviathan at a Soviet military complex. Thompson is sent to stop the sale and apprehend Stark, and is forced to take Carter when she enlists the help of her war comrades, the Howling Commandos. They discover that young girls are trained at the complex to infiltrate the US as sleeper agents, and realize that they have walked into a trap when one girl kills the Commando Junior Juniper.
Soviet soldiers attack the team and Thompson freezes under fire, but Carter ensures that they escape, along with imprisoned psychiatrist Dr. Ivchenko. Meanwhile, Underwood, who is actually a sleeper agent trained at that complex, discovers the photos of Stark's weapons in SSR custody when searching Carter's apartment, while Sousa realizes that Carter is the woman who has been interfering with the SSR's investigation.
Credits
Adapted from Wikipedia contributors, Agent Carter season 1. HTML formatting and reference markers removed.