Deliciously schlocky historical fantasy hidden in the pre-teen section. Authored by Elizabeth Marie Pope.
Kate Hutton, gangly and brainy eldest lady-in-waiting to a pre-coronation Elizabeth I is exiled due to her sister Alicia's excessively teenage letter to Mary I, then-queen of England. Blamed for the letter, our heroine is swept off to the titular Perilous Gard, and soon swept up in the criminal affairs of an endangered fae species engaged in a smuggling and human-sacrifice business.
Kate spends the following few days getting to know the local brooding love interest and being mistaken for a hippie cultist. She soon commits acts of minor heroism and finds herself eating bread and delving too deep into the aforementioned criminal enterprises. The local plotting official swiftly kidnaps her and sends her away with the fairies.
Bored by a life of rich food and drudgery, Kate is soon busy sneaking out of her fairy dormitory under the hill and talking manor drainage with love interest and sacrificial victim Christopher. By day, the heroine is being slowly inducted into the local fairy cult and refusing to inhale local fairy drugs. The author name-checks Tam Lin enough to concuss Kate, who spends the latter half of the novel fainting, yelling at her love interest, and brooding scenically.
The novel finishes off with a vague allegory to driving out noble-yet-beautiful savages, as the fairies are ultimately defeated and peacefully retreat from England. We leave Kate an engaged woman in the early years of the Elizabethan era.