Roddy (voiced tremendously by Hugh Jackman) is a pet rat living the high life alone in his comfy cage when a street rat named Sid rudely interrupts the fun and sends Roddy down the toilet and into the rodent community of the sewer. Frantically searching for a way home, Roddy meets up with Rita (Kate Winslet), a treasure hunter who is being tailed by the evil criminal Toad (Ian McKellen). Striking a deal with Rita, Roddy joins the fight, soon chased by French assassin Le Frog (a playful Jean Reno), and two bumbling henchmen (the wonderful Bill Nighy and Andy Serkis).

Aardman Animation has made a name for itself through its retro, yet pioneering usage of stop-motion animation. Just last year came the delightful "Curse of the Were-Rabbit" feature film that delivered big on both laughs and visual majesty, while also being the rare, clever family film that wasn't a complete drag to sit through.

But times are changing, and "Flushed Away" is Aardman's first fully CG animated production. At first, the effect is quite jarring. Using a program that replicates the jittery movement of stop-motion, it seems pointless for the filmmakers to even try and pass itself off as a faux Plastacine creation, especially when the rest of the movie shimmers with traditional CG smoothness and precision. Everything looks Aardman, from the big gumball eyes to the English overbites, but it has a high-tech touch to it that doesn't digest right when trying to replicate a very unsophisticated process of animation.

Thankfully, an abundance of entertainment in "Flushed" steals the mind away from the technical curiosities. Bathed in a rich history of Aardman English humor and filled out with an international cast of enchanting actors, there's a snap to "Flushed" that saves it from skidding into mediocrity. Directors David Bowers and Sam Fell keep the material dancing at a neck-breaking velocity, bouncing the zingers around like a tennis ball fight, and pushing the voice talent to match the speed of the animated shenanigans. When presented at its most breathless, "Flushed" is rather likable, moving rapidly around British culture jokes and complicated chase sequences through the sewers of London.

When the tempo slows to figure out the emotional journey of Roddy or to spend time with tepid villain Toad, the film comes to a standstill. This can also be blamed on the script, which favors the relationship between Roddy and Rita over the bad guys, leaving Toad's scenes of menace more intrusive than captivatingly evil.

"Flushed Away," with its barrage of Brit quips and a group of Greek chorus slugs who sing the classics, twinkles with wit, but only when it wants to. Thankfully, there's enough of the good stuff in here to make for an entertaining sit.