Revised edition of a 1969 paperback from the Belfast-born British resident author of Dark Night in Toyland, The Peace Machine, etc. In the 21st century, an unknown enemy has dusted the world's croplands with lethal herbicides. With the oceans the only source of food, populations have concentrated along the coasts; one overcrowded city stretches from Maine to Florida. Supplementing the meager marine bill of fare are vegetables produced by robots on platforms, or Iles, suspended five kilometers on high by antigravity machines. When journalist Vic Stirling's half-brother Johnny Considine goes missing, Stirling traces him to the Ile known as Heaven. Here, Stirling discovers a ragged society of misfits, ruled by Johnny and scavenging among the robots and crops--some clever gizmos keep the air in and the temperature up, you see. Power struggles ensue--above (between Stirling and Johnny) and below (between the government and the powerful Food Technology Authority). Threatened by FTA troops, Johnny prepares grandiose schemes to fly Heaven off to the moon. Eventually, Stirling will help the government vanquish both Johnny and the FTA, and begin planning for a fleet of Iles to start the terraforming of Venus. Hard to swallow, sometimes, with too many implausible gadgets; otherwise, professionally burnished if more than a tad stolid.