With the TARDIS disabled in order to undergo repairs, the Doctor is powerless when Romana is kidnapped by a battleship which is on its way to Skonnos and the formidable Nimon.
On Skonnos, Romana and the Athenian youngsters are forced into the labyrinth of the power complex to meet their fate at the hands of the Nimon.
Trapped inside the power complex, the Doctor and Romana begin to suspect that the Nimon is only the first of a full scale invasion.
On Crinoth, Romana discovers the truth behind the Nimon's empty promises.
