The fourth season starts with Michael avenging Sara's "death", before learning that Gretchen did not kill her as he thought. Michael also learns the truth about Whistler, that he has secretly been working alongside Mahone to take down the Company. A Company operative takes Whistler's life shortly after this. Sona has burned down and Sucre, Bellick and T-Bag have escaped during the chaos. After returning to Chicago to look for Sara, Michael is arrested and recruited by Don Self (Michael Rapaport), a Department of Homeland Security agent, to help bring down the Company in exchange for his freedom. Lincoln, who was arrested in Panama is transferred to Chicago along with Mahone, Sucre, and Bellick with whom a deal is made. Also joining the group are Sara, who escaped from Gretchen which resulted in Gretchen's own imprisonment by the Company, having failed to secure a valuable item, and Roland (James Hiroyuki Liao), a hacker who was assigned to help them after getting arrested for identity theft. Together, they devise a plan to retrieve Scylla, believed to be the Company's 'little black book', from the Company that will help to destroy it. In the meantime, Wyatt (Cress Williams), an agent from the Company, attempts to track down Michael and Lincoln. Mahone later murders Wyatt as revenge for murdering his son Cameron. Bellick sacrifices his life in order to save the Scylla break-in. When the group eventually succeeds in stealing Scylla, Self betrays them and tries to sell Scylla, but fails. Right before the mid-season break, it is revealed that Michael and Lincoln's mother is still alive and has obtained Scylla. The 2nd part of the season began on April 17. In the episode "SOB", Michael's mother Christina tells them that Lincoln is not really his brother. She then frames Lincoln and Michael for the killing of the son of India's Prime Minister, in order to precipitate a war between China and India, from which she will profit by selling weapons technology from Scylla to both sides. At the end of the episode "Cowboys and Indians" Michael has acquired Scylla, but Lincoln has been captured by Christina's security and Sara is taken by The General, so Michael must choose between exchanging Scylla for either Sara's life or Lincoln's. In the final two episodes, Michael manages to save Sara by luring the company away from her, then they rescue Lincoln by blowing up the area where he is held. They manage to get help from ex-secret service agent Paul Kellerman and his old friends in order to bring Scylla to the UN. Everyone gets exonerated except for T-Bag, whom the gang decide to send back to Fox River and Krantz, who is sent to the electric chair. The series end with a coda that flashes forward four years to the team meeting to mark the anniversary of Michael's death after the events of the TV movie "Prison Break: The Final Break" in which Michael sacrifices his life to facilitate Sara's escape from prison.
