From the back cover:
This book contains eight main sections
Introduction — in which the basic rules of roleplaying are explained
Creating an Adventurer — in which the system for creating the heroes you will play is detailed
Game System — a guide to the rules for playing the game, which provide its sophisticated pattern of play
Combat — the rules for handling combat man-to-man -- or man-to-beast!
Skills — details of the varying skills and abilities each unique character may learn
The World — rules for developing the realism of the world around you.
Creatures — varied and exciting creatures, with detailed descriptions and complete stats.
Magic — the three forms of magic that bring the fantastic into reality.
User summary:
This is the basic rules for RuneQuest 3rd edition. It has a companion book called Advanced RuneQuest. Together they cover the same material as RuneQuest Deluxe Edition.