It really pissed me off that the creators thought it was a funny idea to scramble the episode, so we could barely understand what was going on. Here's what I gathered:
*SPOILERS FOR PUSSIES WHO CAN'T READ*
After the whole 'ORB' debacle, Brock get's fatally injured and is fixed by OSI by combining HELPER's head with his heart or something. Thinking he's going to get brainwashed or tortured, Brock escapes while still recuperating and see's the boys one last time before giving Dean his communicator watch. Brock then stay's with the six million dollar man and sasquatch from season one, presumably making him fat in the process.
Meanwhile, Dr. Venture and the boys are having a hard time finding a new bodyguard and since it was revealed that Rusty was using clone slugs to keep the boys alive, now everyone wants him to clone someone or something (most notably Nazis with a dog version of Hitler and 21 with the remnants of 24). Eventually, the Venture compound hires Sgt. Hatred as their bodyguard and the boys aren't happy about, especially Hank. Sgt. Hated proves his loyalty by having Hank shoot him in the arm (albeit accidentally).
Back with Brock, he infiltrates Molotov and Hunter's mercenary for hire headquarters in order to kill the two. While climbing through the air ducts, Brock comes into contact with another assassin planing to kill Molotov and Hunter. With their combined weight, they fall from the air duct and onto Molotov, obviously signifying that they are trying to kill Hunter and her. After a heated battle, Molotov shoots Brock into the streets below, where the friends of the assassin from before take him into a van and take Brock to a secret warehouse. After a long questioning, it is revealed that Hunter was faking being a woman the whole time and is still with OSI as an even more secret organization.
At the Venture compound, everyone tells Dean to kill his dog, Super Adventure Boy (a.k.a. Hitler's soul in a dog's body). Staging a very complex chain of events, Sgt. Hated, Dean, Hank and Dr. Orpheus try and kill dog Hitler, while Dr. Venture is tied to chair and being interogated by the Nazis. After using the same effects from the face melting scence from Raiders of the Lost Ark, the Nazis face's are melted, Dr. Venture is safe and Dean is mourning over the loss of his dog.
In the final scene, dog Hitler comes back for Hank, when suddenly out of nowhere, Brock kills it with a golden dagger while looking like his old self and reveals to Hank that he's coming back, but not before helping Hunter and his secret organization in some big mission or something. He also tells Hank not to tell anyone and quickly leaves before Sgt. Hatred could see him, thus ending the episode.
*SPOILERS OVER*
I tried to be as detailed as possible, but also editing the non-important stuff out. Tell me if I missed anything.