Watch Teenage Mutant Ninja Turtles, Allies Unleashed!

Donatello breaks into a secret Kraang detention center in order to rescue Kirby O'Neil. But when he discovers they are trapped inside with a deadly mutant prisoner, he realizes that breaking in was the easy part.

Michelangelo befriends an unstable mutant alligator who possesses a strange piece of Kraang technology, but the other Turtles aren't sure whether Leatherhead is a friend or a foe.

When the Rat King returns, Splinter must overcome his guilt and fear of the Rat King controlling his mind in order to defeat his foe once and for all.

April tries to resume a normal teenage life, but when Karai starts hunting her again, April realizes she may have put her new friend Casey Jones in danger as well.