In the past, Concussion was one of the two leaders of a superhero group called "Team Zenith", along with his brother Jack Shepard, aka Captain Zoom. One day, their ally Dr. Grant tried to increase their powers by exposing them to a radiation called "Gamma-13", however it not only made Concussion more powerful, it also drove him crazy. He decided to kill his teammates, then he fought his brother who created an explosion to kill him, but he was sent into another dimension instead.
Thirty years later, Dr. Grant discovers that Concussion is about to return in our dimension and a new Team led by Zoom is formed. When Concussion finally returns, his brother tries to talk to him but he refuses to listen and attacks him with his sonic blasts. Shortly after, he is confronted to militaries and easily defeats them, then the new Team arrives and attacks him. After a short fight they manage to send Concussion into a vortex created by Zoom, and Dr. Grant informs him that if he closes the vortex he can removes the Gamma-13 from his brother. It fortunately works and Concussion is brought back to normal.