Why are the Daltons trying to get inside a penitentiary?

Transferred to a new penitentiary, the Daltons are put in a cell with Fennimore Buttercup, a counterfeiter who soon begins to regret having such noisy cellmates. To get rid of the annoying brothers, he sends them on the trail of his – made-up – stash: $100,000 buried at the foot of a boulder in Red Rock Junction. One prison escape later, pursued by Lucky Luke, they discover to their horror that the spot they seek ... is inside another penitentiary!

The 58th adventure of Lucky Luke, and the Old West at its funniest!