Episode 4 of Invincible season 3 starts with Rex reluctantly heading out grocery shopping with Rae. However, a monster appears outside, distracting them from the humdrum of everyday life. Meanwhile, Mark brings the remnants of the robot stalking the family to the rabble of Guardians. It’s too ruined to figure out who exactly sent it, but whoever made it clearly has significant resources at their disposal. Naturally, Mark believes this is the work of Cecil and shows up to confront him. Mark punches his way into the Pentagon but when he doesn’t get the answers he wants, he flies off. Although Cecil is still spying on Mark, they’re certainly not using these circular robots, which of course we know. Between this robot malarkey and seeing Eve, Mark is not having a good day. This is especially true when Drop Kick and Fightmaster – the duo who stole the Declaration of Independence – show up in Paris via a glowing portal. Mark and Eve are trying to have a date but the pair ask for help, given they’re from the future. Despite initially refusing, the pair whisk Mark across to the future through their portal, where America is a ravaged wasteland. Turns out centuries back one man was made ruler of Earth. While he ruled well for a while, something changed and he slowly went mad. New laws and mandatory work camps were just the start, before big wars broke out when the rebellion ensued. This duo of heroes stole the Declaration of Independence to try and find a solution, stopping this Mad King before it’s too late. The King’s crazy strength is partly why they needed to find someone just as strong, which led them to Invincible. The trio intentionally get captured to be brought to the King, but it turns out he’s been waiting for them. So who is this King? Well, it’s Immortal! He’s not happy about being left alone to be ruled, given he’s not a Viltrumite and Mark was supposed to be in charge. The Immortal started hurting people to entice Mark back after he left. Mark needs to end Immortal’s torment and also repay some sort of debt he owes from the past. Immortal pleads with Mark to kill him so the power can return to the people. Mark refuses initially, until a fight breaks out between them. Eventually Mark does kill the King, ripping his head off and presumably saving the world. Power is transferred back to the people. Despite making it back home, Mark is torn up over having to kill the Immortal. He returns to Eve and explains the situation, including how he’s messed everything up and is wracked with guilt. That is, until Eve decides they should continue their date which ends swimmingly.