Persisting On The Edge. A doomed globe has become the refuge for the Aidennians. Commander Capel and his crew of the Pioneer 4 notice their life-raft world is undergoing changes. After checking meteorological data, the crew learns that a severe spatial firestorm is coming which will raise planetary temperatures to eventually become superheated. The world's tri-suns are found to be on a countdown to detonation. The only course open to the Aidennians is to repair their impaired ship and evacuate.