The Castle Keeps is a novel written by Andrew J. Offutt. It was first published in 1972.
Earth was in chaos -- could civilization ever return to the planet of terror? The Andrews' hilltop home has become a fortified castle. Jeff Andrews has only the ancient weapons to protect his isolated family from the ravages of roving bands of 'rippers'. The Caudills in the city seem more secure in the protection of their sealed-up apartment building. But they too are gripped by terror, struggling against the hardships of their artificial environment and the dangers that lurk outside.