Michael Sheriff is the top agent at Management Information Services.
His history prior to his work at MIS is sketchy. The most known is that he was married for a while and that he had worked as an agent for the CIA, although it isn't known how long.
When he is not globetrotting or working at MIS headquarters, a non-descript building dubbed 'the Fort' on Route 128 north of Boston, he spends his time refurbishing his home. It was a pre-Revolutionary War house which he has painstakingly restored to its past glory.
At work, Sheriff is the main troubleshooter for the Chairman, the head of MIS. That corporation's main business is information gathering, for which it has the largest computer system 'outside the Pentagon'. This intelligence is sold to the highest bidder as long as the would-be client is acceptable to the Chairman, a man whose dedication to Right is his only religion.
Sheriff practically worships the Chairman and would not envision ever refusing an order, at least until they butt heads over the proper handling of Sheriff's son. The head of the prestigious MIS, the Chairman, whose name is not revealed, may place an extremely high price on the services of his company but he chooses his clients well with the aim of world stability. Michael Sheriff is his best agent and he has taken a stern-but-loving approach to handling the Shield.
Almost as important to the series is Roger Sheriff. Separated from his father as a very young boy when his parents divorced, he seldom heard from, and even more rarely saw in person, Michael. Nevertheless, when he graduated high school it was to his father's house he came. Soon he would be seeking to enter the world of espionage his father worked in.