A tour de force. On one level are stories of the soldiers, scholars, and spies who ventured during the last two centuries into the rugged mountainous territory, from Iran to Tibet, that made up the nebulous border between the Russian and British empires. They were serving either Britain or Russia -- or were believed to be. Later, a few Americans and Germans joined in, combining adventurous trekking with national interest. All the accounts, diligently documented, evoke a Kiplingesque derring-do. At another level, these stories assess the strategies and characteristics of empires: the "forward school" bent on pushing imperial boundaries ever outward, the phobia over what the imperial enemy is up to, and the reluctance to abandon territory once gained. Especially well presented are the ill-fated British interventions in Afghanistan that presaged the later Soviet experience. The authors give the last word to a retired great-game player: it was just a game "with scores, but no substantive prizes."