The final episode of Season 2 has Katrina, Brattina and Catgut finally capture Cooler. To make sure he doesn't escape or find his way back, they drive all around the US multiple times, in circles, in a van clearly labeled "Dog Snatcher." They eventually get pulled over by a policeman for doing 780 miles an hour, and he advises them to at least do 600. During the stop, Cooler escapes, leaving them to eventually empty the back of the truck over a cliff... and just when they realizes he's escaped, the cliff crumbles beneath them, depositing them in the river.
Katrina Stoneheart's Sanity Slippage over having to be around puppies all the time in "Secret Agent Pup", especially when it culminates with her believing that she is a dog herself.