go in search of the golden fleece
To embark on an adventure, often one that is very dangerous or challenging. In Greek mythology, Jason and the Argonauts went on a quest to find the golden fleece of a winged ram. The fossil hunters' descent into the cave is like the modern version of going in search of the golden fleece!
fleece
tv. to cheat someone; to steal everything from someone. (Underworld.) Sam fleeced the kids for a lot of money.