Study Guide

The Sentinel

by Arthur C. Clarke

The Sentinel Summary

Summary (Comprehensive Guide to Short Stories, Critical Edition)

Wilson, a geologist, recalls his role twenty years earlier as leader of a lunar expedition to a massive plateau, the Mare Crisium, or Sea of Crisis. Although the name is portentous, initially the journey appears to be mundane. Wilson even laments that there is nothing hazardous or especially exciting about lunar exploration. It is, he claims, an uneventful routine.

Wilson’s expedition is well equipped. Traveling from the main lunar base, some five hundred miles away, the crew is laden with heavy equipment, including overland tractors, rockets, and scientific sampling machinery. It appears they have little to fear from the unknown. They are in constant radio contact with their base and can survive for a month in their pressurized tractor cabins if there were an emergency.

The men live in relative comfort during their tour of duty on the moon. Short wave radio contact with earth provides ubiquitous music for the men as they dine on freshly cooked food. This particular expedition, however, soon deviates from the routine. While preparing his breakfast sausages, Wilson observes a glint of what appears to be a metal object on a far mountain bordering the plateau. Against unanimous dissent from his crew, Wilson and his assistant, Garnett, journey to investigate the object.

After scaling a ten-thousand-foot-high mountain at the edge of the plateau, Wilson discovers a small crystalline pyramid. He initially believes that it was created by...

(The entire section is 431 words.)