All life on Earth is held hostage by a ruthless alien race in this "hard-hitting apocalyptic thriller" from the award-winning author of Orbis (Booklist).
The Tarsalans came to Earth hoping to settle on the planet alongside a sympathetic human race. But after years of delicate negotiations, their patience reaches the breaking point and they decide to make their case for immigration terrifyingly clear-by enveloping the planet in a green sphere which blocks out all sunlight.
Without energy from the sun, the Earth-and every living thing on it-is doomed.
Soon, civilization breaks down as the instinct for individual survival shreds humanity's common bonds. It appears mankind may destroy itself even before the Phytosphere does.
The only hope against catastrophe lies in the troubled connection between two brothers-one stranded at a lunar base on the moon, the other trapped on the dying Earth...
"Deftly juggling hard sci-fi and a bleak tale of post-apocalyptic survival" Scott Mackay once again offers an electrifying tale of "high-tech intrigue and old-fashioned suspense" (Publishers Weekly).

Vicki Ann Heydron met Randall Garrett in 1975. In 1978, they were married, and also began planning the Gandalara Cycle. A broad outline for the entire Cycle had been completed, and a draft of The Steel of Raithskar nearly finished, when Randall suffered serious and permanent injury. Working from their outline, Vicki completed the Cycle. Of all seven books, Vicki feels that The River Wall is most uniquely hers. The other titles in the Cycle are The Glass of Dyskornis, The Bronze of Eddarta, The Well of Darkness, The Search for Kä, and Return to Eddarta.