To the Savants the Dodecahedron is a miracle of science to be studied, observed and used to benefit Tigellan civilisation. To the Deons it is a god and not to be tampered with.

When the power supply begins to fluctuate wildly the whole planet is threatened, but the Tigellans cannot agree how they should deal with the problem.

Zastor welcomes the arrival of the Doctor and invites him to arbitrate, but the Deons are suspicious of the Time Lord - and perhaps rightly so...
 

When the Dodecahedron, the mysterious source of all power on the planet Tigella, goes out of control, the survival of the whole planet is threatened. Zastor, leader of Tigella rules over a divided people: the Savants and the Deons, who have vastly differing views on how to rectify the situation. Zastor welcomes the arrival of the Doctor, hoping he'll mediate and find a solution. However, things are hrown into jeopardy when the Dodecahedron is stolen and the Doctor is arrested as the thief and condemned to death! Someone, somewhere, is, messing around with identity - someone who wants to take control of the Dodecahedron for their own selfish purposes.