As the young Sebastian, gamers take the role of the son of a brilliant scientist who has discovered a means to travel through time. Time travel has already taken place in this reality, however, and Sebatian's first mission is to use his father's discovery to return to the past and destroy an earlier time machine, which upset the balance of power in a past war and led to dangerous realities in their present. Just as Sebastian enters the machine to travel back to the past, he watches helplessly as his father is kidnapped and taken prisoner.
Now trapped in the past, Sebastian must find the ancient time travel device and destroy it to set events right in his own time. But he must also find a way to travel back to his own time, in order to rescue his father from his captors. As if the situation weren't paradoxically impossible enough, an agent has been sent from the future to hunt Sebastian down and stop him at all costs.