Mark Grayson is just like everyone else his age, except that his father is the most powerful superhero on the planet. And now he's begun to inherit his father's powers. It all sounds okay at first, but how do you follow in your father's footsteps when you know you will never live up to his standards? Invincible is enlisted to accompany the first manned space flight to Mars. What secrets could the red planet hold? Why would someone anticipate a problem necessitating the inclusion of the most powerful superhero on the planet? Invincible is about to find out, and the answer will astound you!

Invincible escorts a shuttle to Mars. The astronauts encounter 'Martians' and another alien race called the "Sequids".