Farscape S02E20 - Liars, Guns and Money Part II: With Friends Like These...

The crew is stunned when they learn that Scorpius has bought the slaves out from under D'Argo. Rather than trade Crichton for Jothee, Crichton, D'Argo, Aeryn and Rygel seek out mercenaries to help them steal the slaves. In the process, they encounter some enemies they've fought in the past. Meanwhile, back on Moya, the stolen money has turned into metal-eating spiders that begin to consume Moya.