On a bitter winter's day in 1916, deep below the streets of New York, a group of men is working in one of the huge pressurized tunnels that will make up the subway system. Suddenly, a tiny hole appears in the roof of the tunnel and the air rushes in, sucking the men up through the bed of the Hudson, to be suspended on a spume of water high above the river. Almost 90 years later, Treefrog, a homeless man, stumbles through the same corridor, under the twirling flakes of snow, to his makeshift under the city. survival.