With the alien ship on the monitor and Mrs. Salazar in control of the EMP device, the cadets aboard the Conquistador are in a bind. When the alien ship makes a run for it, the humans give chase. But when they capture it and breach its hull, they don't expect to find the Enemy within. Jack is asked to teleport back to camp to put down the invaders who've taken it over and killed off his fellow cadets and teachers. Can he rise to the challenge?