Corridor to Nightmare - Dave Duncan - Bog

When one life ends, another begins.
After forty years as the village school teacher in the idyllic valley of Greenbottom, Agatha is looking forward to a quiet retirement. Instead, an enigmatic stranger arrives to drag her through a long-closed portal to another world.
Confronted with a completely foreign culture steeped in magic and violence, Agatha finds herself a crucial pawn being played between rival factions. The only way forward through the rigid traditions and convoluted politics of the Archons of Otopia is to remain true to herself and her Greenbottom ideals.