Into Thin Air by Jon Krakauer — Krakauer's account of the 1996 Everest disaster is the most gripping Himalayan narrative ever written, and though it focuses on Everest rather than Annapurna, it remains the essential book for understanding the culture, the ambition, and the danger of Himalayan climbing.
Annapurna by Maurice Herzog — Herzog led the 1950 French expedition that made Annapurna I the first 8,000m peak ever climbed. His account of the summit bid and the brutal descent, during which both summiteers lost most of their fingers and toes to frostbite, is harrowing. The style is old-fashioned — very 1950s France — but the experience he describes is real and extreme.
The Snow Leopard by Peter Matthiessen — Matthiessen's 1978 account of a journey through the Dolpo region north of the Annapurna range is one of the great travel books: part natural history, part Buddhist meditation, part grief memoir. The landscape and atmosphere he describes — the same arid Tibetan plateau found in Upper Mustang — is more philosophically demanding than most trekking narratives.
Touching the Void by Joe Simpson — Not Annapurna specifically, but the most gripping survival story in mountaineering literature, by two climbers who were the first to summit Siula Grande in Peru. The psychological honesty is instructive for any high-altitude trekker about what the mind does under extreme stress.