After a mishap with a portal, the Turtles and their human allies find themselves joining the Rainbooms at Camp Everfree where there's mystery and magic in the air. With the Rainbooms gaining new magical abilities, they take their next step in their ninja training to learn to control their new powers and defend their friends from a danger lurking within the camp itself.

Sequel following the events of Equestria Ninja Girls in Space. Recommended to read before this.