He first appears, jealous of Lucky because of all the attention and advantages she gets, tells her that she's a bird and that her adoptive father wants to eat her.
Lucky runs away and gets captured by Great Big Rat's minions. The cats look for her all over the town until they found out that Great Big Rat has her captured. The cats build a big cheese and hide in it (a trick they learned from the Trojan Horse). YoYo however goes alone into the sewers and stops the rats before they can eat Lucky, but both of them end up captured. The cat's cheese arrives just in time as the cats jump out and rescue Lucky and YoYo right before Great Big Rat could kill them. The cats throw Great Big Rat and his sidekick into the canals.
Zorba and his friends then decide to teach Lucky how to fly. Lucky fails to successfully fly until Zorba decides to teach her to fly as a seagull mother would. For this Zorba asks Bubulina's owner, a little girl named Nina, to take them to a very high tower where Lucky could jump from the top and, according to her instincts, be able to fly. Lucky tells Zorba that she loves him, calling him by his name for the first time, and he tells her that he loves her, too. The plan succeeds and Lucky starts flying. The Great Big Rat sees the commotion and becomes enraged that his plan failed. Before she leaves she (Lucky) grabs YoYo and brings him to Zorba. Lucky then says good-bye to Zorba. YoYo calls Lucky his little sister, before Lucky gives her first seagull call and joins a flock of seagulls.