After years of being sheltered from the human world, the Turtle brothers set out to win the hearts of New Yorkers and be accepted as normal teenagers through heroic acts. Their new friend April O'Neil helps them take on a mysterious crime syndicate, but they soon get in over their heads when an army of mutants is unleashed upon them.

Marcel is an adorable one-inch-tall shell who ekes out a colorful existence with his grandmother Connie and their pet lint, Alan. Once part of a sprawling community of shells, they now live alone as the sole survivors of a mysterious tragedy. When a documentarian discovers them amongst the clutter of his Airbnb, his resulting short film brings Marcel millions of passionate fans, as well as unprecedented dangers and a new hope at finding his long-lost family.

A charming thief and a band of unlikely adventurers undertake an epic heist to retrieve a lost relic, but things go dangerously awry when they run afoul of the wrong people.