Lucky Luke - Volume 58 - The Dalton's Stash

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!