There are several suspects. For example, his indifferent wife, Sylvia (Kristin Scott Thomas), who, after all, has to live with him. There's Constance (Maggie Smith), a snob and gossip whose allowance from Sir William has been threatened. And so on, and so forth.
Major cast members include Sir William's daughter Isobel (Camilla Rutherford), a famous Hollywood actor (Jeremy Northam), an obscure Hollywood actor method acting as an obnoxious servant (Ryan Phillippe), a Hollywood producer (Bob Balaban) gathering background material for a Charlie Chan epic, a homely society woman wed for her dowry (Claudie Blakely), the head valet (Alan Bates), the head maid (Helen Mirren), the head cook (Eileen Atkins), an incompetent inspector (Stephen Fry), and an orphanage-raised valet (Clive Owen).
How others will see it. Director Robert Altman isn't known for prestige films, but he sure knows how to cast them. Helen Mirren and Maggie Smith have played bluebloods in countless period pieces, and predictably, both received (yet another) Academy Award nomination for their efforts in Gosford Park. The well-received film is the very stereotype of what is expected of a "class" movie. Droll dialogue, intrigue, gossip, supper club singing, rude behavior, a pretty girl, a cad, and a dash of sex and murder.
How I felt about it. Gosford Park has about 40 named characters, which is about 30 more than can be followed by the average viewer. Ten minutes into the movie, no more mortal besides the director and screenwriter can clearly distinguish between Isobel, Mabel, Lavinia, and Louisa, let alone the plethora of servants.
There is a thicket of subplots, including several minor ones that should have been left on the cutting room floor, such as the obese servant (whats-her-name #14) who shags another servant (whats-his-name #17).
As expected from Christie-like mysteries, there are blatant clues that point to the wrong culprit. Experienced mystery fans know that Freddie Nesbitt (James Wilby), no matter how desperate or obnoxious he may be, cannot be the murderer, because it is too obvious a conclusion.
But the viewer also expects a complete solution. Who shot Sir William? Who poisoned him? Who stabbed him? Who made him watch "Full House" reruns? (Okay, that crime is unimaginably fiendish and is not actually part of the movie.) Needless to say, the guilty parties are uncovered, with the mystery solved by none other than the youngest-looking servant, Mary (Kelly Macdonald).
This is the 'groaner' portion of the movie, not the (expectedly) ridiculous combination of murderers and motives. Mary, the prettiest and most modest woman in the entire cast, is also apparently the smartest, since she not only figures out whom both killers are, she gets them both to confess to her and explain why they did it. She's better than Perry Mason! And without a law degree or years of courtroom experience!