Short summary of the story, The Under Graham Railroad Box Car Set, from Five-Carat Soul?

In the story, The Under Graham Railroad Box Car Set, a toy collector named Leo Banskoff seeks a model train designed by Robert E. Lee just before the Civil War as a gift for his son Graham. Leo finds the train's owners in Queens, New York, a Rev. and Mrs. Hart. Mrs. Hart tries to give the train to Leo because she and her husband are devoutly religious and uninterested in material things. He insists on giving them $90,000. Leo is unsatisfied with his remarkable find, however, because the Harts are reluctant to tell Leo how the train came into their possession. He wants the train's story. Once he has all but given up, Leo tracks Rev. Hart to a hip hop club in Brooklyn. Inside, Leo hears Rev. Hart perform a rap about the evils of slavery and the punishment God continues to mete out upon mankind for these evils. Leo walks away from the performance feeling redeemed.