Prison Break Season IV Premiere.

To avenge Sara's death, Michael follows Gretchen to Los Angeles, planning to kill her while she and Whistler are on a mission to retrieve a card containing crucial information about the Company. 

Held at gunpoint, She confesses that Sara had escaped and the head was a fake. 

Unaware that Whistler has made a copy of the card, Gretchen goes to meet the General, who is intolerable of her fault and orders Waytt to kill her.

Mahone and Whistler are now working together against the Company; they try to enlist Michael's help, by promising to reveal Sara's whereabouts. But Whistler is shot in the head by Waytt when trying to convince Michael in an alley. 

In Panama, Lincoln kills a man sent by the Company before surrendering to the police to protect L.J. and Sofia. Bellick and Sucre escape from Sona after a riot takes place and is smuggled back in the U.S., where they are apprehended by the police while Sucre is visiting his baby daughter. 

T-Bag also escapes and resolves to revenge himself on Michael; on his way back to America, the smugglers rob him, taking his money, leaving him in a desert. After talking to his wife on the phone, Mahone joyfully heads home to reunite with his family; much to his grief, he arrives at home only to find them brutally murdered.

In Chicago, Michael contacts Bruce, a trusted friend of Sara's father, in the hope that he can shed light on Sara's situation, but is arrested before he can get any information. He is approached by Agent Donald Self, a Homeland Security official dedicated to bring down the Company, and requested to infiltrate a Company facility to decrypt the card, in exchange for his freedom. Before he can respond, Bruce bails him out, driving him to a secluded house where Sara is waiting for him; they embrace.

At night, Waytt tries to assassinate them, but fails, prompting Michael to accept Self's offer.A team consists of Michael, Lincoln, Sucre, Mahone, Bellick and Sara board a plane to start their mission, and they will all be free once the mission is accomplished.