Geologist Henry Stanwick leads a pleasant enough but rather dull life as a professor in a second-rate British university. When an offer comes from American adventurer Tim Vaughan to take a trip through Madagascar's bizarre & hazardous limestone formations known as the pinnacles, part of Stanwick welcomes the invitation, & part of him feels a vague dread.
It's not just the dangers posed by the pinnacles--the cliffs that shut out the sky, the lifeless landscape, the fact that fifty yards in you can be lost forever.
No, it's something more fundamental. Is Vaughan who he says he is--just someone looking for an unusual challenge--or is he hiding something? Why does Stanwick's stolid fellow professor Abie Gvirtzman turn glum & talk cryptically about "prophetic instints" whenever Stanwick mentions Madagascar? How does the annoying & mystifying computer game Vaughan sends Stanwick fit into the mix? Who or what is Jezreel?
Only in the depths of the pinnacles does Stanwick begin to realize the horrible truth about Vaughan--& about himself, with his own heart of stone.