Invincible is a coming-of-age story in a world with superheroes. Mark Grayson (voiced by Steven Yeun) is a fairly typical teenage boy -- going to high school, trying to make friends and figure out girls -- with a mom and dad in a small, suburban home. The difference in Mark's world is, his dad Nolan (J.K. Simmons) is secretly the superhero Omni-Man, a strange visitor from another planet with Superman-like abilities.

This animated series is based on an Image line of comics by The Walking Dead creator Robert Kirkman, who also adapted the series for television. Although I haven't read the books on which the series is based, it looks like animators adhered closely to the comics' original style.

Back to the story. Although Omni-Man is easily the strongest of the heroes, there are others. Foremost among them are the Guardians of the Globe, analogous to the Justice League, with powerful crusaders including Warrior Woman (Lauren Cohan), Martian Man (Chad L. Coleman), Red Rush (Michael Cudlitz), Darkwing (Lennie James), The Immortal (Ross Marquand) and Green Ghost (Sonequa Martin-Green). There are also other groups and solo crusaders, but Omni-Man and the Guardians are the cream of the crop.

In the first episode, Mark finally develops powers of his own, and his father eagerly begins his training while his human mother (Sandra Oh) frets with worry. He also stands up to a bully at school, gets a girlfriend (Zazie Beetz) and other, fairly mundane stuff; the first episode is a little dull, and I was actually wondering if I would bother finishing the eight-episode series ... and then came the shocking ending. The entire Guardians team is slaughtered in a brutal, graphically depicted battle, leaving only Omni-Man alive, though badly wounded and locked in a coma.

As the authorities try to figure out who killed the Guardians, Mark -- now with his own tailored supersuit and using the optimistic name Invincible -- and other heroes try to fill the void, as various threats rise to meet them. Soon Mark, who only recently had few worries more desperate than his school exams, is facing global and extraterrestrial emergencies alongside second-tier heroes like Atom Eve (Gillian Jacobs), Rex Splode (Jason Mantzoukas), Dupli-Kate (Melise), Robot (Zachary Quinto), Monster Girl (Grey Griffin) and Black Samson (Khary Payton).

The series at times focuses on the dull and ordinary stuff of a teenager's life: dating, part-time jobs, school drama, etc. But it's also quite dramatic at times, with some pretty extraordinary plot twists and over-the-top violence. (This series is not for the squeamish.) Full disclosure: Viewers will know from the first episode who the killer is, although other characters won't learn the truth for a while. I won't spoil the big reveal here, however; if you're curious, watch the show.

It's worth your time, if you like adult-oriented comic-book material. The season finale seems to promise more to come.

By the way, fans of Kirkman's most famous comic-to-television property might enjoy hearing the vocal talents of a lot of Walking Dead stars in the cast of Invincible.