Synopsis
Sentry was supposed to be fighting on Iron Man's side in the big battle in Civil War #3-4. But he couldn't bring himself to fight friends. He could kill them all - it would be easy for him. But then the enemy-self Void might return (even though he threw him into the Sun). So now he's run away to the Moon to think about what to do. He could take control and stop the whole thing. (His mental image shows Hulk helping him. Hulk will do anything he says. But Hulk isn't around anymore - he's on Sakaar, Planet Hulk.)
But he's forgotten that the Inhumans live on the Moon now. He's approached by some of the royal family (Crystal, Gorgon, Karnak, Triton and Lockjaw the teleporting dog) plus some others. He remembers them from an adventure he shared with them against Red Ronin in his previous superhero career that the world has forgotten about. (This adventure was recorded in the now-missing Startling Stories #92.)
Bob Reynolds greets them in peace but Gorgon attacks him, followed by others. Crystal keeps out of the fighting. After his initial surprise, Sentry easily holds them off. But Crystal gives him a replica of Black Bolt's antenna and a bottle of wine(?), which he interprets as a summons to parley. Lockjaw transports them to the king's audience chamber.
Medusa speaks for her mute husband and asks Sentry what he's doing there. Bob says he just wanted to be alone, and then he was attacked. Medusa says it's because the Inhumans are at war with humans, which is news to Reynolds. Gorgon doesn't believe his ignorance, but a mind reader confirms it.
The seer also discovers his memory of fighting alongside the Inhumans against Red Ronin, which the Inhumans themselves have no memory of. She uncovers the story of how a mutant forced Sentry to make the world forget about his earlier exploits. But now he's back and an Avenger.
Now it's the Inhumans turn to discover their ignorance of current affairs as the seer learns about the existence of the Civil War. Medusa allows Bob to explain what's going on to her family over dinner. He says that Nick Fury's Secret War against Latveria increased paranoia, which led to House of M and the mutant Decimation. This made things even worse and produced the Superhero Registration Act. Now the superhero community is split between the Act's supporters and a Resistance who refuse to register.
Gorgon's still not happy, but Sentry is invited to stay the night.
Crystal brings Bob some more food that night. She felt a connection between them and asked the seer about Sentry's previous time with them. She learned that they had briefly become lovers, which Bob confirms. Apparently it was when she'd just broken up with Human Torch. Crystal makes a move on him now, but he pulls away because he's married.
The situation is defused by the arrival of Iron Man to bring Sentry back to the War. IM needs him to win the conflict. Bob doesn't think Captain America will give up until they kill him. Tony Stark is sure that they can take Cap alive, and eventually he'll come to see that Stark's vision of the future is good. Sentry can help shorten the War before too many people get hurt. And afterwards the world will need heroes like Sentry.
Then this conversation is interrupted when the rest of the royal family pop in to arrest Iron Man for coming here uninvited. Shellhead blasts blustering Gorgon, but now it's Sentry's turn to defuse things by agreeing to leave with Stark.