After The Chipmunks demand newer technology, Dave drags them unwillingly on a camping trip. When they finally arrive and set up camp, the boys believe they've seen Bigfoot. Dave convinces them there is no Bigfoot and they look for food. Theodore finds some honeycombs that attract a bear who chases them to a bridge. The bridge breaks along with Dave's ankle. After the boys make a tree-house for Dave, Alvin and Simon go look for help but run into Bigfoot instead. While fleeing they determine that Bigfoot is really Shifty, a reporter.
- The title is a spoof of classic novel The Swiss Family Robinson by Johann David Wyss.