In 2005, one of Washington’s enduring mysteries was solved when former FBI Associate Director Mark Felt revealed that he was “Deep Throat.” He had been so named by The Washington Post, to whose reporters he provided leads about the unfolding Watergate scandal. Those troubled months are recounted in this straightforward docudrama from Peter Landesman (Concussion). Liam Neeson portrays Felt, a square-jawed G-man. The film lays out how he came to leak, suggesting variously that it was pique (at being passed over for director), an effort to protect the FBI (which had its own extra-legal problems) or a larger sense of patriotic duty. Previous knowledge of Watergate is helpful — this film doesn’t have time to explain who Mitchell, Erlichman or Dean are — and newbies will be further confused by a cast that is nearly all bland middle-aged white men in suits. On one level, it plays out as a high-level office drama, the proverbial snake-pit of bad feelings, ambition and secrets; it’s just that what everybody was shuffling around was explosive. The White House was attempting to squash an FBI investigation; the CIA was sending memos; and, in essence, one part of the FBI was investigating another. “No one can stop the driving force of an FBI investigation,” states Felt. “Not even the FBI.” Recommended for Watergate completists, and perhaps those interested in some of the specific gears of the impeachment machine.