The Five Million refers to the money Charles Westmoreland was in possession of.
Charles revealed to Michael (and to T-Bag and C-Note too, as they are presence) that it was not only one million he robbed as D.B. Cooper, but five million. It is hidden in the Double K Ranch in Tooele, Utah. Most people doubted it but since it is the only hope that they have, Michael, Lincoln, Sucre, T-Bag, C-Note and Tweener decided to dig out the treasure.
T-Bag met Tweener in Tooele, both of them looking for a treasure. Later, Michael and Lincoln found T-Bag exiting a library which contained a map of the Ranch. T-Bag, however, ate the paper and forced Michael to cooperate with them. C-Note was able to access the U.S. Army website and locate the Ranch. He hitchhiked Sucre, who was riding on a motorcycle. They successfully dug out the five million but T-Bag tricked the convicts and took the five million. Tweener was arrested and murdered in this action.
Bellick and Geary were able to find T-Bag and took his money. T-Bag had actually installed a GPS system in the bag that contained the millions, thus he found Geary, killed him and took the money. Later, the money was taken by Michael. After this, Lincoln throws the money on the floor of a dock, telling Bill Kim, who is holding the brothers at the gun point, that he didn't care about the money. Kim kicked the money in the sea in disgust.
Much of Season 2's storyline develops around the five million. This includes....
- Charles Westmoreland's imprisonment (Imprisoned Prior to Season 1)
- Tweener's arrest
- Geary's death
- Bill Kim's death
- Sara is wanted and missing