The Cabal — David Hagberg

In Washington, CIA operative Todd Van Buren meets with a Washington Post investigative reporter who has uncovered strong evidence that a powerful lobbyist has formed a shadowy group called the Friday Club, a cabal whose members include high-ranking men inside the government: a White House adviser, a three star general at the Pentagon, deputy secretaries at the State Department, Homeland Security, the FBI and even the CIA.
That afternoon Van Buren, son-in-law of the legendary spy Kirk McGarvey, is brutally gunned down because of what he's been told. The same evening the reporter and his family are killed, all traces of the shadow group erased.

A grief stricken McGarvey is drawn into the most far-reaching and bizarre investigation of his career, the stakes of which could destabilize the U.S. government, and shake the foundations of the world financial order.