TMNT Vol. 15: Leatherhead is also collected as part of Teenage Mutant Ninja Turtles: The IDW Collection Volume 7.
As the Turtles continue to get used to a world leading the Foot Clan post-Shredder, they return to the Technodrome to moniter the revival of the Utroms on Burnow Island. They are surprised to meet a new mutant-Leatherhead! Will the mysterious mutant be friend or foe?