On the face of it Santaroga seemed like any other small California town in an agricultural valley. But this one had its own — unofficial — rules.

Outsiders found no houses available to let or for sale.

G.I.'s always returned there on discharge.

No Santarogan ever left the valley.

No chain Supermarket could open there.

Were they simply "last-ditchers"? Or was there some other explanation, physical, psychological or even extraterrestrial?

Gilbert Dasein, pshychologist, with an old college girl-friend living there, went to try to find out. It wasn't any of the things he thought it might be and some of his investigations led him into strange paths before he was able to pass through The Santaroga Barrier.