During HYDRA's mental reconditioning of Winter Soldier, a string of code phrases were implanted into his mind: "Longing, rusted, seventeen, daybreak, furnace, benign, nine, homecoming, one, freight car." After hearing these phrases spoken in Russian, Barnes becomes completely obedient to the speaker, and would carry out whatever task he was ordered to accomplish.
In 1991, the code phrases were uttered by HYDRA officer Vasily Karpov, who ordered Winter Soldier to steal the recreated Super Soldier Serum and eliminate any witnesses. Winter Soldier complied, killing Howard Stark and Maria Stark.
In 2016, Helmut Zemo planed to use the Winter Soldier book as part of his plan to make the Avengers fight each other. He went to Vasily Karpov's home in Cleveland and stole the Winter Soldier Book from him, after killing him.
In a hotel room in, Berlin, Zemo practiced the code phrases to control the Winter Soldier. Zemo disguised himself as a psychiatrist hired by the Joint Counter Terrorist Centre to interrogate the captive Winter Soldier. During the interview, Zemo caused an power outage and read the code phrases from the book to control Winter Soldier. He used him as a distraction to escape the scene.
Behind the Scenes
- In the original draft of Captain America: Civil War, Helmut Zemo's original goal was to retrieve the "Mind Crown", the key element of the Memory Suppressing Machine, that would have gave Zemo the control over Bucky Barnes's mind. The Russo replaced it with a book because they thought it would have been more convenient into the story.
- Contrary to popular belief, the use of the word "homecoming" and "seventeen" is coincidental and is not a reference to Spider-Man: Homecoming (2017).