Caught in the crossfire, Earth has become the staging ground for a conflict of star-spanning proportions! For those eternal intergalactic enemies, the merciless Kree and the shape-changing Skrulls, have gone to war, and our planet is situated on the front lines! Can Earth's Mightiest Heroes, the Avengers, bring about an end to the fighting before humanity becomes a casualty of war? And what good are even a dozen super-powered champions against the vast military machines of two of the great empires of the cosmos?