Mark looks like a normal teenager, but he isn't. His father is Omni-man, member of the Guardians of the Globe. Though he looks like a normal human, he's actually an alien from another world, but Mark's mom is human, and his father attempts to live a normal life, pretending to be a writer who is often gone on reasearch trips.
Meanwhile, Mark lives a normal life; Attends high school, has a job at a burger place, and hangs out with his friends. But when he finally comes into his powers, the world becomes a much larger place for him- not only is he helping clean up his town, taking on a Superhero name "Invincible" and getting a costume from the same place his Dad got his, he starts hanging out with The Teen Team: Robot, Atom Eve, Rex Splode and Dupli-Kate.
Then Mark's Dad gets pulled into an alternate dimension for a few days Mark's time, eight months subjective time, and Mark discovers that one of his teachers is turning kids into human bombs in retaliation for the death of his son. Soon after, the Guardians of the Globe are killed, and Mark's friend AtomEve discovers that her boyfriend, RexSplode, is cheating on her with DupliKate- and his friend William finds out his secret.
With the death of the Guardians, Mark's Dad seems more distant- even his wife notices. But as Robot it tapped to head a new Guardians of the Globe, and Mark and Robot's former Teen Team members try out for spots on the new team, Mark finds his life suddenly going to shit- and his love life (or lack thereof) are only part of the reason. First one of the members of the Guardians of the Globe, Immortal, comes back from the grave, and he knows who killed the other Guardians- Omni-Man, Mark's Dad.
Their subsequent fight lets the world know who killed the Guardians, and when Mark hears about it, he goes ballistic and goes off to fight his Dad- where he learns that the story his Dad told him, and his mother, isn't true. Mark's Dad didn't come from a Utopian world, but one where the genetically perfect and superior conquered and overthrew the rest. Mark's Dad was sent to conquer Earth, and he pretended to be a hero for so long because he wanted to ensure that he knew all the would-be heroes he'd have to fight when the time came to conquer Earth.
He views Mark's mother as nothing more than a pet- and Mark himself as a threat if he won't join his father in conquering Earth. But Mark refuses, even though his father is really giving him a beating. He'd rather die than betray the people of Earth of whom he is one, no matter his origin. But when his father flies off, leaving Mark alive, can his alter-Ego, invincible, become the nucleus of Earth's defense against his father's people when they inevitably return to invade? How will Mark, who couldn't even stand toe to toe with his father, be able to deal with that?
Storywise, I really enjoyed this comic compilation. It's an interesting, well-told story that takes a rather obvious cliche and turns it on its head. "Son of a well-known Superhero" whose father turns out to really be a villain, not a hero. Yet signs point to Mark being able to think up some way around the invasion. If his father is indicative of the people on his planet, Mark might very well be able to out-think them, and get people to join him based on his charisma.
On the other hand, I found the art more problematic. While it was nice to see tributes to and pastiches of various comic book and science fiction heroes (The Guardians of the Globe are rip-offs of the Justice League, complete with analogues to Batman, Martian Manhunter, Green Lantern, Wonder Woman, Flash and Aquaman, but members of the WildC.A.T.S. and the Savage Dragon show up at the Funeral, along with a character who, from behind, looks just like Rorshach from Watchmen. There's even a place where the alienized cast of Star Trek:TNG makes an appearance. On the other hand... I didn't really like the art style. It felt too cartoony, and a bit too stylized. YMMV, of course, but I just never really got used to it, even later in the book.
In large part, I was reading the book less for the art than the story, which I found compelling. The art was barely on the level of "Nice" for me, but I'd rather have a well-written book that looks like crap than have a gorgeous artwork that tells a story that's crap. I know which one I'd find more interesting to read, anyhow.
Nevertheless, this book is worth it just for reading the story, and the story here is excellent. The artwork is merely pedestrian and does the job of carrying the tale around, but it isn't anything to write home about for me. I'd recommend it, again, based almost completely on the story and not much else.