Mark Felt: The Man Who Brought Down the White House is a mouthful of a title, but I guess Deep Throat was already taken. Felt was the fabled anonymous source that provided the information to Washington Post reporters that ultimately exposed the full scope of the Watergate conspiracy. The Post’s Bob Woodward and Carl Bernstein’s side of this story was presented onscreen in All the President’s Men. Now it’s Felt’s turn. Bernstein never appears in the film, and Woodward only has a brief cameo. But in its tone and style, Mark Felt plays like a companion piece to All the President’s Men, illuminating the motivations of the man who was Watergate’s greatest mystery.

Alan J. Pakula’s film about Woodward and Bernstein, made long before Felt’s secret became public knowledge, featured a Deep Throat played by Hal Holbrook.  Whether Holbrook or Pakula knew the truth, they actually got pretty close to Felt’s look and demeanor, or at least the version of him featured in The Man Who Brought Down the White House. Played by Liam Neeson, he’s a stern, imposing, perpetually smoking figure lurking in the shadows of Washington. He’s rarely seen without a cigarette in his hand and he’s never seen wearing anything but a crisp, dark suit.

In hindsight, Felt’s motivations make perfect sense. In The Man Who Brought Down the White House, he’s presented as the ultimate company man, an FBI lifer with an absolute commitment to law enforcement and the Bureau’s carefully guarded autonomy. When longtime FBI chief J. Edgar Hoover dies in 1972, Felt believes he’s the most qualified candidate to replace him. But his loyalty to the FBI over the White House gets him passed over in favor of Nixon loyalist Pat Gray (Marton Csokas). When the Watergate break-in happens soon after, Gray tries to shut down the FBI’s investigation, while Felt fights to keep digging. Eventually, he’s left with no other choice but to go to the press.

If you’ve taken American history or seen the earlier movie, you know what happens next. The reason to watch Mark Felt anyway is to observe Neeson in this role, scowling and smoking and sweating out the toughest choices this man (or almost any man) would ever have to make. In the years since Taken revitalized his career, Neeson has made significantly fewer movies that actually require his skills as an actor. Mark Felt is a reminder that he can do a lot more than rescue imperiled family members and punch terrorists in the neck.

There are other subplots too, although they don’t add much to the picture. Diane Lane plays Felt’s long-suffering wife, who has dutifully followed him to over a dozen different postings during his 30 year career. Their college-age, left-leaning daughter Joan (Maika Monroe) has gone missing, and Felt suspects she may have fallen in with a group of counterculture revolutionaries. He could use his position at the FBI to locate her, but what he uncovers could also put Joan in legal jeopardy.

It’s yet another difficult decision Felt is forced to make, and it adds a personal dimension to Felt’s order (one that later led to his conviction for a serious crime) to surveil members of the Weather Underground without proper warrants. But for the most part, Lane and Monroe’s portion is a distraction from Mark Felt’s best stuff, the scenes that dig into the uniquely territorial culture of the FBI. Many of the finer points, like the way the executive branch tries to influence investigations or the importance of writing memos, has taken on renewed relevance in recent months. But Felt’s story would be compelling without them, particularly if you’re a fan of paranoid thrillers featuring a lot of very extremely gruff character actors standing around in shadowy rooms threatening one another. (The impressive supporting cast includes Josh Lucas, Tom Sizemore, Tony Goldwyn, and Bruce Greenwood, just for starters.)

The screenplay, written by director Peter Landesman and based on books by Felt and John D. O’Connor, does a fine job of condensing a sprawling conspiracy into a digestible feature, although it sometimes favors clarity over nuance and winds up enunciating important plot points in glaringly unnatural dialogue. (At one point, a character notes that the investigation needs to resolve by November 7, and another goes “November 7? Election Day!” just in case anyone in the audience has never heard of the concept of Presidential elections.) The outcome is never in doubt — but it was never in doubt in All the President’s Men either. These movies aren’t so much about their plots as illuminating the lives of the heroes behind the headlines and their insistent mood of dread at the dawning realization that our most treasured institutions have been infiltrated by criminals. When that happens, all that stands in their way are men of integrity — and even they, as Mark Felt makes clear, may not have entirely altruistic motives. So amongst the many lessons of Watergate, here is another: If the guy who knows all your deepest darkest secrets wants a promotion, you should probably give it to him.