New York, August 1974: a man is walking in the sky. Between the newly built Twin Towers, the man twirls through the air. Far below, the lives of complete strangers spin towards each other: Corrigan, a radical Irish monk working in the Bronx; Claire, a delicate Upper East Side housewife reeling from the death of her son; Lara, a drug-addled young artist; Gloria, solid and proud despite decades of hardship; Tillie, a hooker who used to dream of a better life; and, Jazzlyn, her beautiful daughter raised on promises that reach beyond the skyline of New York. In the shadow of one reckless and beautiful act, these disparate lives will collide, and be transformed for ever.

On a bitter winter's day in 1916, deep below the streets of New York, a group of men are working in one of the huge pressurised tunnels that will make up the subway system. Suddenly, a tiny hole appears in the roof of the tunnel and air rushes in, sucking the men up through the bed of the Hudson, to be suspended on a plume of water high above the river. Almost ninety years later, a homeless man stumbles on the same corridor and sets about making his home deep under the city.