The Theft of the Mind Stone was a plan executed by the Avengers as a part of their Time Heist to acquire the Mind and Space Stones in New York City, during and after the Battle of New York. They remained unsuccessful in stealing the Space Stone, however, which prompted Iron Man and Captain America to go even further back in time to April 1970.
Ant-Man, Iron Man, Hulk, and Captain America were tasked with going back in time to the Battle of New York in 2012 to retrieve the Mind Stone, Space Stone, and Time Stone. While Hulk was tasked to retrieve the Time Stone, Iron Man and Ant-Man, were tasked to obtain the Space Stone, and Captain America was to attain the Mind Stone.
During the aftermath of the Battle of New York, Stark notices the 2012 Avengers gathered in Stark Tower, as they are preparing to meet with the "STRIKE agents" to hand them the Scepter. Stark alarms Rogers that his cue is coming, and Rogers says he is en route via elevator. Stark quietly infiltrates the building as he eavesdrops on the 2012 Avengers with 2012 Loki. Stark makes a snarky remark to Rogers that his old suit did nothing for his ass, leaving Lang (in a small size standing on Stark's shoulder) to joke that that is "America's ass". Stark quietly watches as the STRIKE team arrives and 2012 Black Widow hands them the Scepter. As the STRIKE agents secure the Scepter, Lang asks who they are, and Stark answers that they are HYDRA agents posing as S.H.I.E.L.D. agents, however at this particular point in time the Avengers were not aware of this. As the agents and the Avengers separate, Lang and Stark plan on securing the Tesseract as Stark flies outside, informing Rogers that the agents with the Scepter are on the elevator passing the 80th floor.
Rogers copies and tells Stark they will rendezvous in the lobby, as he prepares to enter the elevator with the agents, posing as his 2012 counterpart. As Rogers enters the elevator, Jasper Sitwell questions Rogers for abandoning his search and rescue mission, prompting Rogers to answer that there was a change in plans. Rogers and Brock Rumlow awkwardly greet each other. Rogers tells the group that the secretary ordered him to take control of the Scepter, as there may be an attempt to steal it, however Sitwell and Rumlow are skeptical and refuse to hand the Scepter over. Rogers earns their trust by whispering "Hail HYDRA" in Sitwell's ear, successfully leaving the elevator with the Scepter.
As conflict arises and Lang and Stark fail their mission to retrieve the Tesseract, Rogers asks them what is going on but they do not answer. Rogers then finds himself confronting his 2012 counterpart, who believes he is facing Loki transformed into himself. Present Rogers says he is not Loki and wishes not to hurt his past self, but past Rogers quickly goes on the attack. The two fight an even match until they both fall to the floor below, as past Rogers notices present Rogers' discarded locket with Peggy Carter's picture. Past Rogers asks present Rogers where he got it, but locks present Rogers in a headlock as he tries to secure the Scepter. Thinking quickly to save himself, present Rogers tells his counterpart that Bucky Barnes is alive, prompting the past Rogers to let his guard down in confusion, only to be knocked unconscious as present Rogers uses the Scepter on him. As present Rogers secures Peggy's locket and the Scepter, he confirms to himself that that is "America's ass" as he makes his way to the lobby.
Rogers rendezvous with Stark and Lang, who inform him of their failure in retrieving the Tesseract. After a small dispute, Stark suggests that he and Rogers travel further back in time to the 1970s, where they can retrieve the Tesseract as well as extra Pym Particles to make the return journey. Stark and Rogers, putting their trust in each other, go forward with the plan, as Rogers hands Lang the Scepter and tells him to return back to 2023, where the stones were later used to reverse the Decimation. After the Battle of Earth, Captain America traveled back to return the Mind Stone to when it was taken.