To avoid social problems during the winter period, Anvhar has initiated a planet-wide series of mental and physical games called the Twenties.
As he recovers from the games, Brandd meets Ihjel, a previous winner of the Twenties, who manages to convince him to join a mission on the desert planet of Dis.
The ruling class of Dis, the magter, have threatened to transport cobalt bombs onto the neighbouring planet Nyjord if they refuse to surrender.
After encounters with the local population and other humans, Brandd starts to put together the reason for the magter's seemingly suicidal aggression.
Eventually Brandd locates the cobalt bombs and disables the transmission mechanism, allowing him to return home.