After Tony Stark discovers the body of a Skrull shapeshifter, the Skrull Empire launches an invasion and the Avengers, the X-Men, Spider-Man, and many other heroes are forced to fight against themselves while wondering which of them is an imposter. Secret invasion is here! The shape-shifting alien race known as the Skrulls has secretly infiltrated every super-powered organization on Earth with one goal: full-scale invasion.