Gripping and thoughtful, Emily St. John Mandel’s “Exit Party” brings two grim speculative futures together in a single narrative.

One possibility sees the United States in the aftermath of a second civil war. In Los Angeles, the peacekeepers have left, the curfew has lifted, but the nation is not what it once was. Militias and gunrunners rule large swathes of the country as refugees in encampments try to carve together new lives.

On another earth, there isn’t disorder to speak of, but that’s because the United States have given way to the surveillance of a single State. It’s the kind of place where family members inform on one another, and black vans whisk dissidents away, never to be seen again.

“Exit Party” introduces us to the same cast of characters in these different spaces, exploring, “Sliding Doors” style, the people each of us could become. On one Earth, Ari is a jailbird, newly freed from an 18-year sentence after trying to arrange a hit on her cousin. On the other, Inari has a career in “Service,” the bleak investigators and enforcers of the State. Mandel uses the split to explore how the same person can bend in different directions, how our fundamental self is expressed according to our surroundings.

The book’s twist takes place when the two worlds intersect for a moment, the result of a physics experiment gone wrong. This shifts a few characters to the other dimension, where they have to figure out how to live new lives while never fully leaving behind their old ones.

Mandel does excellent work with the characters and setting–I was hooked from the start. Even as the narrative slows when we get past the rush of the first sections, I remained enmeshed in her vision of a domed Paris, a California where surveillance drones hover overhead. These future visions are paired with deeper questions, like “What makes a bad parent?” and “Is criminality some kind of calling?” The author doesn’t have easy answers for us, but her characters have an appealing dimensionality and warts.

If you’ve read her other books, some familiar elements make an appearance here: a painting, some artists, a general preoccupation with transport and self. The book itself is in some ways a sequel to Mandel’s “The Singer’s Gun,” although you don’t have to have read that to understand this one.

“Exit Party” does slow in the later sections, and the author takes it easier on her characters than her set-up demands. Both the collapsed U.S. and the Orwellian one leave gaps for the characters to move the plot forward, and not all of these slips are convincing. But Mandel’s voice and vision are engrossing, making for another rewarding read.

Quotes

“I knew the bomb was the reason she was the way she was, why she flinched at loud noises, why she avoided leaving the apartment, why she was such a goddamned ghost in this world, but the unkind thought that flitted through me was Get over it. How long after the terrible event do you get to be a ghost? I knew the question made me a bad person.”

***

“‘I think if you live long enough,’ Nico said, ‘you become a migrant from another timeline. There’s the world you learn to navigate as you enter adulthood, and then the world slips away from you by degrees and after a while there’s nothing left of it, but you’re still here.'”

***

“Sometimes, living in this country felt like living at the end of the world. He tried to accept this, tried to find some meaning in it. Who will you be at the end of the world? I tried to be a good parent. I tried to be a good friend.