COGAN'S TRADE by GEORGE V. HIGGINS 216 pages. Knopf. $5.95. "Mark Trattman's game got hit a couple nights ago."
"Somewhere around fifty-three thousand they got?"
"Two kids. They had long hair and they smelled like animals. Trattman said."
"The last time, I gather, the man who did it actually was Trattman himself."
"We start with Trattman and we start real good."
The conversation takes place in a silver Toronado parked on Tremont Street in South Boston. The man in the driver's seat is a lawyer representing a family the Cabots do not speak to....