The Unknown Known (2013)

But Morris's movie is a cat-and-mouse game, and Rumsfeld is the cat, virtually licking his chops as he toys with, and then devours, another rival.

Ranging over familiar material, but made vivid by Morris' fecund associations and invigorating stylistic flourishes.

Morris tediously recycles points he already made in his 2008 look at the Abu Ghraib prison scandal in Standard Operating Procedure.

Though watchable, the film pales in terms of enjoyment and insight in comparison to Morris's last film interview with a former Defence Secretary, Robert S. McNamara, in 2006's The Fog of War.

Rumsfeld takes this to another level, giving contradictory answers at different points throughout the interview.

The Unknown Known delivers the type of nuanced, fascinating portrait we've come to expect from Errol Morris, and avoids offering simplistic conclusions about Donald Rumsfeld.

Morris asks the occasional tough question, but he's never particularly aggressive. And with Rumsfeld...still the career politician, he ultimately proves too slippery for his interviewer, who fails to get...real reflection or revelation out of him.

That enigma -- whether Rumsfeld has ever doubted his public frontage, whether his most contentious war strategies were born of profound belief or tactical stopgapping -- is one Errol Morris doesn't really come close to penetrating.

If documentaries slotted into feature film genres, this one would be close to horror.