Winter, 1745. Scotland is losing a war for independence. Robert Maxwell and his fellow soldiers beg for supernatural aid from the daione sìdhe, magical inhabitants of Scotland exiled in ancient times to a parallel plane of existence. The sìdhe ask to negotiate with the Scottish leaders, who rashly enter into a magical contract promising the sìdhe a permanent return to Britain in exchange for their help in the war.Access to sìdhe soldiers and magical weapons gives the Scots a temporary advantage, but their agreement lacks stipulations to prevent lone sìdhe creatures from hunting humans, stealing children, or riddling the countryside with hidden portals that can whisk passers-by into parallel dimensions. Worse, the sìdhe leaders seem unable to stop the chaos.The Scottish leadership work to understand the sidhe and find a way to coexist. But they find sìdhe are not as disorganized as they appear, and harbor a sinister goal: to end the war on their own terms and secure their claim on Britain, no matter what the cost to their human allies.