A Brooklyn plumber named Mario travels through the Mushroom Kingdom with a princess named Peach and an anthropomorphic mushroom named Toad to find Mario's brother, Luigi, and to save the world from a ruthless fire-breathing Koopa named Bowser.

As the Avengers and their allies have continued to protect the world from threats too large for any one hero to handle, a new danger has emerged from the cosmic shadows: Thanos. A despot of intergalactic infamy, his goal is to collect all six Infinity Stones, artifacts of unimaginable power, and use them to inflict his twisted will on all of reality.