The TARDIS takes the Doctor and Sarah to the planet Zeta Minor on the edge of the universe. An unseen menace has wiped out an Morestran expedition and haunts the alien jungle.
The Doctor and Sarah are held responsible for the deaths on Zeta Minor, but the Doctor knows that the real culprit comes from the mysterious universe of antimatter.
In the universe of antimatter, the Doctor communes with the creature and makes a bargain.
The rebels seize control of the aliens' HQ but the Doctor is forced to send a call for help to his own people, the Time Lords.
The Doctor is captured by the War Chief, who belongs to the same race of people as the Doctor, and offers an alliance. In the 1917 zone, fighters prepare to attack Central Control.
