On Marinus, the Daleks and Voords were fighting one another, when the Daleks learnt that the Voords knew of a mushroom known as the Great Power that granted superhuman abilities. If the mushroom's juice was taken into their brain cells, it would give the Daleks enough brainpower to outwit any threat. The Daleks pretended to form an alliance with the Voords.
Discovering the First Doctor, they forced him to hand over the secret of ultkron travel. The Doctor, having been taken on board the Voord spaceship by the Daleks, secretly sent a signal to the solar system, but was uncertain which planet the Daleks and Voords were heading towards.
The Doctor told the Voords about the Daleks' plan to destroy them. The Voords attempted to round up the Daleks, but one Dalek escaped and freed the Daleks. A fight broke out between the two species. A Dalek raygun hit the ship's power centre, disintegrating the ship. The Daleks evacuated on their hoverbouts, while the Doctor and the lone Voord survivor, the Chief Voord, escaped in an escape capsule.
The Chief Voord took over the capsule and aimed it for the South American jungle on Earth. The Daleks followed. Earth Space H.Q. ordered fighters to intercept, killing many Daleks, but were forced to pull back once the Daleks reached the jungle. Knowing that the fungi were deadly, the Chief Voord led the Daleks to them. The Daleks' increased brainpower allowed them to shoot down another fleet of Earth fighters, but the Daleks suddenly dropped dead. The Chief Voord was killed by the falling hoverbouts. (PROSE: Doctor Who and the Daleks)