First, with Cybertron under siege from Baron Ironblood, it's up to Optimus Prime and Arcee to defend their homeland, and the Revolutionaries team is caught in the middle! Then, back on Earth, Rom finds himself teaming up with the world's smallest heroes, the Micronauts! Can they prevent catastrophe, or is it already too late? And, with the team divided, G.I. Joe must confront dangers both in space and Earthside. Looks like they'll need some help from M.A.S.K.!