Humans first bumped heads with the Taurans when we began using collapsars to travel the stars. Although the collapsars provide nearly instantaneous travel across vast distances, the relativistic speeds associated with the process means that time passes slower for those aboard ship. For William Mandella, a physics student drafted as a soldier, that means more than 27 years will have passed between his first encounter with the Taurans and his homecoming, though he himself will have aged only a year. When Mandella finds that he can't adjust to Earth after being gone so long from home, he reenlists, only to find himself shuttled endlessly from battle to battle as the centuries pass.