Already longlisted for the Booker Prize, Rachel Kushner’s “Creation Lake” stars a ruthless American secret agent.

The story is set in rural France, but not the rural France of guidebooks and Peter Mayle memoirs. No one rhapsodizes over an escargot or a tarte Tatin. We’re in the country’s southwest, where the soil is rocky. More essentially, we are in what Kushner calls the proletarian “real Europe,” with vistas of “highways and nuclear power plants” and “windowless distribution warehouses.”

Kushner’s narrator is an American spy-for-hire. She’s 34, a dropout from a Berkeley Ph.D. program in rhetoric. She is working under an assumed name, “Sadie Smith.” Smith has come to this region to infiltrate a radical farming commune bent on violence.

Biographical details about Smith are scant, though the reader is made aware of two of her previous assignments. At 24, she infiltrated the Gypsy Jokers motorcycle gang, where she was the “old lady” of an older biker she put in prison. Later, she convinced a troubled young man to buy 500 pounds of fertilizer for bomb making. When he was found innocent at trial due to entrapment, she was fired by the F.B.I. and went freelance.

The farming commune is called Le Moulin. Smith is well-read in the history of radical movements, but as she befriends the group’s key members, she imbibes their philosophies and absorbs the revisionist ideas that have been passed, like batons, down generations. The leader, Pascal, is a womanizer and a self-styled heir to the French Marxist theorist Guy Debord.

His writings — he exists largely in the form of email dispatches — argue that Neanderthals might have been better adapted for the planet. Smith has an arsenal of tools to monkey-wrench the monkey wrenchers — a willingness to exchange sex for access, a knack for languages and hacking, well-made cover stories, fake passports — but her work among the Moulinards stokes her own identity crisis. As she enters their world, she processes their enthusiasm, their philosophy, and their paranoia, which escalates as some minister plans a visit to the region, upping the stakes.