A war between two factions outside the Solar System threatens Earth. A wayward missile in that war hits the sun (and destroys a starliner en route), and this causes the sun's nuclear fusion to go out of control. In one Earth year, unless the fusion is corrected, the sun will burn the Earth and all life will cease to exist. Also, in three years, the sun will explode and destroy the solar system. The Argo, now officially captained by Derek Wildstar, is commissioned (with new cadets) to search for a new home for the people of Earth.