Dorothy 'Dottie' Underwood / Ida

Dottie Underwood arrives at the Griffith as its newest resident, bright-eyed and full of small-town cheer. Landlady Miriam Fry presents her to Peggy Carter and Angie Martinelli as a fresh transplant from Iowa, chasing a ballet career in the big city. Dottie is all easy friendliness, gushing that the place feels like one big happy family and marveling at Peggy's English accent, since she has never met anyone from across the pond. It is a brief, sunny introduction, a farm-country girl finding her footing among the women of the Griffith.

Dottie Underwood continues presenting herself as an innocent young woman living at the Griffith Hotel while secretly observing Peggy. Her apparent friendship with Peggy and Angie allows her to remain close to Peggy's activities without drawing suspicion. Dottie's true nature, however, becomes much harder to dismiss when she encounters Otto Mink.

Mink arrives at the Griffith intending to kill Peggy, but Dottie notices his unusual automatic pistol and becomes interested in taking it for herself. She quickly turns the encounter against him, using her extraordinary physical ability to attack and kill him before taking his weapon.

Dottie Underwood appears to Peggy as a seemingly friendly new neighbor and accompanies her to breakfast. She presents herself as an innocent young woman interested in experiencing New York, allowing Peggy to offer advice about the city and its people. With a moment of faked clumsiness, Dottie steals the key to Peggy's apartment, showing her apparent friendliness is a calculated deception.

Dottie was trained as a child in a Soviet assassination program. She learned to fight, endure harsh discipline, and kill without hesitation. Her relationship with another trainee, Anya, briefly provides a glimpse of genuine friendship before Dottie is forced to kill her during training.

Dottie appears in a flashback to Ivchenko’s recruitment into Leviathan, where she kills a man who refuses to join the organization. In 1946, she enters a dentist’s office under the guise of a job applicant. When the dentist behaves lecherously, Dottie turns the encounter into an interrogation and murder, then uses the office across from the SSR as an observation point.

From the office, Dottie receives Ivchenko’s Morse-code order to kill Peggy. She returns to the Griffith and plays the frightened, innocent neighbor when Peggy tries to leave. Dottie uses the knockout lipstick she stole from Peggy to drug her with a kiss. Peggy sees the restraint scars on Dottie’s wrists and recognizes the truth just before collapsing. Dottie prepares to kill her, but Sousa and Thompson arrive in time for Dottie to surrender Peggy to the SSR under a false innocent-witness story.

Dottie operates from a position across the street from the SSR while maintaining communication with Fennhoff. She receives his Morse-code messages and prepares for the next stage of Leviathan's operation. Peggy observes the communication and identifies Dottie as the person receiving Fennhoff's instructions.

After escaping the Agents sent to collect her, Dottie picks Fennhoff up as they plan to test his stolen Stark tech. She works with Fennhoff to activate the gas cylinder inside a crowded cinema before and locking the doors behind them leaving the movie goers to their violent end.

Dottie assists Fennhoff in the operation against Howard Stark. She creates a false impression that she is attempting to assassinate Howard during his public appearance, but the rifle has been rigged to fire above the podium. Peggy and the SSR realize that the shooting was intended as a diversion rather than an assassination attempt. The confusion is used to remove Howard from the scene via a mind controlled police officer.

Dottie later meets Howard and reveals that they had previously spent a weekend together. She accompanies him to his private aircraft hangar, where she helps deliver him to Fennhoff. When Peggy reaches the hangar, Dottie attacks her. Peggy and Dottie fight, with Dottie using her physical training and ability to imitate Peggy's movements. Peggy eventually defeats her, but Dottie escapes before the SSR can capture her.