Uncertain Terms - Patrick J O'Brian - Bog

After learning of a threat against his family, Boston cop Mike Brogan returns to his hometown of Chicago to work for a secretive agency promising to keep his wife and children safe. Using state-of-the-art technology, Brogan monitors activities between the local mafia, a biker gang from New Mexico, and the corrupt police family he left behind years earlier. A war is brewing between the factions, certain to end in bloodshed with no regard for collateral damage.
Thrown into illicit activities with former military operatives, Brogan realizes he's out of his element. Unwilling to trust everything the agency's leadership tells him, the cop must remain hidden, and anonymous, to the outside world if he wants to see his family again. Until the threat is eliminated, Brogan cannot quit his new work, but with each new mission he risks being discovered, arrested, or killed.
He soon realizes the group harbors bigger plans for him, and as the stakes grow, and good people are killed, Brogan is left with the impossible choice of returning to his family, or assuming a leadership role, to carry out worldwide good behind the scenes.