After settling in Green Hills, Sonic the Hedgehog (voice of Ben Schwartz) is eager to prove that he has what it takes to be a true hero. His test comes when Dr. Robotnik (Jim Carrey) returns with a new partner, Knuckles (voice of Idris Elba), in search of a mystical emerald that has the power to destroy civilizations.

Sonic teams up with his own sidekick, Tails (voice of Colleen O'Shaughnessey), and together they embark on a globe-trotting journey to find the emerald before it falls into the wrong hands.