Roddy is a decidedly upper-crust "society mouse" who lives the life of a beloved pet in a posh Kensington flat. When a sewer rat named Sid comes spewing out of the sink and decides he's hit the jackpot, Roddy schemes to rid himself of the pest by luring him into the "whirlpool." Sid may be an ignorant slob, but he's no fool, so it is Roddy who winds up being flushed away into the bustling sewer world of Ratropolis. Now he has to get used to a completely new and unfamiliar world…