Star Trek Original Series No. 77. Unlike most planets, Rimillia does not spin upon its axis, so the day and night sides are subjected to perpetual extremes of heat and col. Habitation has only been possible on a narrow strip of the planet's surface. Until now...Using gigantic impulse engines of unimaginable power, the alien Dumada intend to start Rimillia rotating, making the entire world fit for colonisation. Yet there are those who fear the enormous stresses involved may instead tear the planet apart. Assigned to assist the Dumada, Captain Kirk must rescue a kidnapped scientist vital to the rotation project. But once the giant engines are activated, can Scotty save Rimillia and the Enterprise from total destruction?