Johnny Worricker, the hero of the new "Masterpiece Contemporary" film "Page Eight" (Sunday at 9 on PBS), is in British intelligence, but not in the James Bond sense. He may occasionally don a tuxedo for professional reasons, and he's irresistible to a certain kind of woman (the lonely kind, mostly), but his job is to sit at a desk, study the reports that come across it, and figure out what they mean.

And it's a specific piece of paper that gives "Page Eight" both its title and its central conflict. Johnny has been in the game a long time, as has his boss and best friend Benedict, and while those years add wisdom, they can also create ennui. So it takes Johnny quite a while to notice there's something very wrong on page eight of his latest report, and even longer to realize what that means and what he has to do about it.

"Page Eight" was written and directed by David Hare, who wrote the scripts for "The Reader" and "The Hours" but is a playwright by trade. And there's a very stage-like quality to the film, much of it consisting of Johnny sitting in conference rooms and drawing rooms discussing his life, his legacy and the current state of British intelligence with friends and colleagues, most of them played by a murderer's row of British (and/or Australian) character actors. In addition to Bill Nighy as Johnny, we have Michael Gambon as Benedict, Judy Davis as their colleague Jill, Rachel Weisz as Johnny's inquisitive neighbor Nancy, Ralph Fiennes as the British prime minister, Alice Krige as one of Johnny's many ex-wives and Felicity Jones as their estranged daughter.

These thespians(*) sit around and utter lines that are larded with meaning, as when Benedict explains to Johnny, "This building is swimming in information. We have information coming out of our ears. So the difficult thing is to notice when someone finally tells you something."

(*) Some, but not all, of them have figured prominently in the Harry Potter films (even Nighy briefly played the Minister of Magic), making this a very Hogwarts double feature with next week's "Masterpiece" film, "The Song of Lunch," starring Alan Rickman and Emma Thompson.

And when "Page Eight" is just these fine actors tossing clever dialogue at each other and contemplating the inexorable passage of time, it's marvelous. Bill Nighy in particular delivers a kind of master class in minimalism. Johnny's inflection rarely changes, his expression only slightly more, and yet there's so much in his eyes about regret, and rapidly closing doors, and the reasons behind his unexpected burst of heroism over the course of the film. He's fantastic.

Yet the first half of the movie, before we learn quite what's on page eight and what that means, begins to feel like a shell game after a while. Hare wants to keep the pieces moving around without showing you what's underneath them, because he's not entirely sure what's there or what to do with it once he finds out.

As the movie heads into its second half, it takes tentative steps towards being a genuine spy story. Johnny goes rogue, has to shake a tail, perform surveillance and other bits of spycraft, and his new friendship with Nancy begins edging into romantic territory. But Hare's heart doesn't seem to be in any of the more conventional parts of the narrative. Weisz's character never really fits into the rest of the film, and the conspiracy Johnny is fighting against seems less a driver for a thriller plot than it does an excuse for Hare to discuss the efficacy of torture.

So long as "Page Eight" sticks to its strengths - great performances, crackling dialogue, a palpable sense of loss - it's well worth your time. It's when it tries to be something it's not - maybe not Ian Fleming, but John LeCarre - that it stumbles.

Alan Sepinwall may be reached at sepinwall@hitfix.com