Thirty years after the end of the world, a young woman enters into a marriage of convenience with a man she hardly knows so she can secure vital medical care for her beloved younger sister.

The world might not have ended all at once. But end it did.

Kayla Hollins is a survivor. Living in the fragmented wasteland of the Canadian Pacific Northwest, she's outlived a colony, a cult, a paramilitary group, and most of her family. So when her younger sister April falls seriously ill, Kayla will do anything to save her. They trek to Salt Spring Island, which is rumored to still have a functioning hospital. But Salt Spring's utopia comes at a price. Not just anyone can enter paradise or access their medical care, and Kayla's past is checkered.

Desperate, Kayla makes a deal with Sid Charles, an aspiring politician she meets on the island. If Kayla and Sid get married, it will boost Sid's chances of election, and grant April automatic access to the medical treatment she needs. And in two years, when Kayla is eligible for citizenship herself, they can get a divorce. Simple, right? The more time Kayla spends with Sid and his ragtag group of rescued boys, the more she comes to admire and care for him. But with April's treatment and Sid's election on the line, Kayla isn't sure she can risk trying to change their arrangement.

Trapped together in the closest thing left to paradise, Kayla and Sid both know what it means for the world to end. As they try to rebuild with the people of Salt Spring, there may be time left to save—if not the world—themselves.