Following an adolescence filled with poor choices and a difficult family life, Marty Roberts leaves his hometown of Weymouth, Massachusetts, in search of a better future. He has a brief stint in the U.S. Navy, becomes a medical photographer, and then eventually settles into a job with a California computer company. But Marty's deeply buried need to reconcile with his past surfaces and propels him to make the cross-country trip back to the Boston suburb.

Marty plans a quick visit-a walk around East Weymouth and along the eighteen-mile Greenbush Railroad line. He thinks he's severed all his connections to Weymouth, but while he's on the South Shore, the past suddenly hits him with all of its drama, pain, and angst. He has to face the demons that have chased him from one place in the country to the next.

Marty reconnects with Harold Asher, a crotchety old man who was one of the solid, steady influences in his early life. A former railroad employee, Harold joins Marty and the two walk the Greenbush line together. It's a journey that takes Marty through both the external and internal geography of his life and ultimately leads him to a stunning revelation.