Newly empowered after his recent battle with Protocide, US Agent is recruited by Val Cooper to lead STARS – the Superhuman Tactical Activities Response Squad – responsible for dealing with super-powered crime.
On an early mission he hauls in the fugitive Piledriver, but in the process discovers one of the alien Blood Brothers. When US Agent reports to STARS headquarters he discovers similar alien convicts have been turning up throughout the United States. A brief interrogation of Reptyl reveals the aliens are not an invading force – they've been sentenced for their crimes to be imprisoned on Earth.
US Agent visits the Avengers' Mansion, where the team has is taking in the sudden influx of aliens on their video screens. The Avengers aren't happy to see Agent, but when Goliath reports a strange, cloaked energy signature hovering in the mesophere the Avengers have no choice but to bring US Agent along to investigate.
The Avengers Quinjet is destroyed en route by a blast from the massive hovering ship, and the entire team is pulled inside via a tractor beam. There they discover a Kree, Ronan the Accuser, presiding over a prison ship laden with complex technology. Ronan explains that Earth has been sentenced to a galactic quarantine, and to ensure the Avengers don't thwart energy fields containing our solar system Earth has also been designated as a galactic prison planet.
When Ms. Marvel tries to reason with Ronan, but he effortlessly teleports the team back to the streets of New York. Back at the mansion US Agent tries to usurp control from Wasp in the name of Federal Authority, but the argument is cut short by a report from STARS – it looks like one of the alien fugitives beamed to Earth was a highly compressed form of Ego – and he is rapidly expanding to turn Earth into his new body!