This Side of Brightness weaves historical fact with fictional truth, creating a remarkable tale of death, racism, homelessness--and yes, love--spanning four generations. Two characters dominate Colum McCann's narrative: Treefrog, a homeless man with a dark and shameful secret, and Nathan Walker, a black man who came north in the early years of the century to work as a "sandhog," digging the subway tunnels beneath Manhattan. Tunneling is perhaps the most dangerous occupation a man could have; in the close, dark, and dangerous pits far beneath the city streets, differences such as color or ethnic background cease to matter, and Walker soon becomes friends with his crewmates: two Irishmen and an Italian. Then an explosion in one of the tunnels literally blows Walker and three other men up through the earth and into the East River. Walker survives, but his best friend Con O'Leary is never found. Leary leaves behind a wife and young daughter whom Walker marries many years later.

Walker's tale is told in alternating chapters with Treefrog's, who, before his slide into homelessness, chose a hazardous profession--this one high up in the bright sunlight--as a construction worker building skyscrapers. But madness has brought Treefrog out of the light and back to the tunnels that Walker helped dig as he scrapes out a meager existence among the drug addicts, alcoholics, prostitutes, and petty criminals that make up the homeless community. But the grimness of McCann's tale is leavened by the beauty of his prose and the intimations all through the book that, even on this side of darkness, redemption is possible.