In House Witness , the twelfth novel in the Joe DeMarco series, Mike Lawson puts his likable protagonist on the trail of a different kind of fixer--one whose job is to influence, and sometimes disappear, witnesses in seemingly airtight criminal cases. Minority Leader of the House and DeMarco's long-time employer John Mahoney has kept more than one secret from his wife over the years, but none so explosive as this: He has a son, and that son has just...