Still reeling from their encounter with Kang, the original Avengers take the opportunity to grab some much needed R&R. While Spider-Woman and She-Hulk are in Boston, tracking the super-powered mercenary called Machete, the rest of the team takes the Quinjet to the White Mountains of New Hampshire, where Thor’s friends Dr. Jane Foster and Dr. Eric Selvig are part of the initial launch of a new, NASA-sponsored, state-of-the-art space observatory.
Arriving on site, the Avengers meet Thor’s friends, as well as their colleague Dr. Phil Lawson, and base security chief, Air Force Colonel Carol Danvers. After a delicious meal (provided magically by Doctor Strange), and several hours of camaraderie and laughter, an alarm let the scientists know that there were two unidentified flying objects approaching the Earth, and that their movement patterns suggested they were NOT space debris.
Thor and Iron Man moved immediately into space to confront these UFOs, which were revealed to be alien craft. One of the craft disabled the other with blasts of energy, sending the injured ship plummeting towards the observatory area, and leaving Iron Man to swiftly gather the debris before it could damage anything on earth. Thor partially disabled the other ship with an electrical field, but was unable to prevent it from landing.
Doctor Strange teleported himself, Wasp, Dr. Selvig, and Carol Danvers to the crash site, where they were able to witness the second craft land and the pilot disembark. He identified himself as Yon-Rogg of the Kree, and dismissed the earth heroes as being between him and his quarry, a “Skrull”. HE then unleashed a giant robotic war machine on the group, which he identified as a “Sentry”.
In the observatory, Scarlet Witch, guarding the other scientists, was surprised at the return of Carol Danvers, and even further surprised when “Colonel Danvers” was revealed to be a shape-shifting alien – a Skrull. Furthermore, this Skrull had the powers of the entire Fantastic Four, and began to attack.
While Thor engaged the Sentry, the rest of the team returned to the observatory with Colonel Danvers in pursuit of Yon-Rogg. There they found themselves in a battle between the Kree and the Skrull. Facing defeat, the Super-Skrull hurled a stolen Kree weapon towards Jane Foster. Carol Danvers intercepted the weapon, throwing herself on it like a grenade. Phil Lawson rushed to aid her, and both were caught in the blast if the weapon exploding. In the aftermath, Colonel Damvers was left in a coma, and “Philip Lawson” was revealed as a Kree infiltrator named Mar-Vell.
With Mar-Vell’s help, Yon-Rogg was defeated, and the Sentry deactivated. Mar-Vell explained to the Avengers that the Kree and the Skrull were ancient races that had been at war for millennia, and that Earth was a strategic position for both empires. Mar-Vell had been assigned to Earth to assess the genetic potential of the population for colonization and experimentation, but had grown fond of Earth and its people, and had been giving false information to the Kree leader, the Supreme Intelligence. Now, with Yon-Rogg and the Sentry both transmitting data about Earth’s super-heroes, Mar-Vell had no choice but to return to the Kree, and attempt to plead a case for non-aggression.
While the rest of the Avengers called in a S.H.I.E.L.D. clean-up crew to deal with the alien wreckage and secure the facility, Doctor Strange and the Wasp teleported Carol Danvers back to New York for medical attention. Fearing genetic damage from the Kree weapon, they sough out Henry Pym for aid, only to find Pym gone, his lab ransacked, and his lab assistants unconscious. They quickly gathered the inured assistants and then sought out Doctor Henry McCoy, the Beast, bringing the Doctor and the three injured to a nearby medical facility.