|Season 2, Episode 1-36|
|Box Top Robbery||Metal Munching Mice|
Bullwinkle receives a letter informing him that his uncle Dewlap has passed on, leaving him a mine located on Mt. Flatten. Rocky and Bullwinkle set out to find it, and soon discover that they're being monitored by not only Boris Badenov and Natasha Fatale, but their old friend Captain Peter "Wrong Way" Peachfuzz, the new head of G-2. Peachfuzz has been sent to make sure Rocky and Bullwinkle find Mt. Flatten, as its ore, the anti-gravity metal Upsidaisium, is much sought after by the U.S. government. While under the guise of a pair of prospectors, Boris and Natasha manage to help Rocky and Bullwinkle locate Mt. Flatten, which floats high in the air due to the high amount of Upsidaisium within it. Once they reach the mountain, Boris and Natasha are joined by their intimidating superior, Mr. Big, who tells them that Pottsylvania also seeks Upsidaisium as a means to eliminate a traffic problem (by building cars with the anti-gravity ore). Eventually, thanks to Rocky's ingenuity, Mt. Flatten is transported to Washington D.C., and the Upsidaisium is put under lock and key by the government. Unfortunately, Boris attempts to smuggle the precious metal out of the government's reach, even going so far as to disguising himself as a U.S. general. Rocky and Bullwinkle are cornered by Mr. Big, but when they attack him, they find that he's really a very tiny individual. Mr. Big escapes into an Upsidaisium vault, and Boris and Natasha are put under arrest. Seizing a bit of Upsidaisium and using Rocky as a hostage, Mr. Big attempts to escape but is carried into the air by his ill-gotten gains, never to be seen again, resulting in another happy ending for the duo.
- This is the first on screen apperance of Mr. Big.