Why did it take more than a decade for Disney’s Pixar to make a sequel to the beloved Oscar-winning animated feature Finding Nemo?

As producer Lindsey Collins explained here at our Contenders event, the think tank at Pixar actually stumbled upon it. After watching Nemo again for a 3D restoration five years ago, director Andrew Stanton felt that he left the story of the short-term-memory fish Dory — unfinished.

Says Collins, Stanton felt that if Dory “got lost again tomorrow, she would not be able to find Marlin and Nemo.”

Here, the Dory and Wall-E producer explains the inspiration for the sequel, which was 2016’s highest grossing title at the domestic B.O. with $486.3M, as well as the Pixar recipe for combining humor with thought-provoking drama.