Alec Guinness doesn't play the protagonist -- instead, he plays the eight surviving members of the noble D'Ascoyne family whom the protagonist intends to murder. The protagonist, whose mother the D'Ascoyne patriarch disinherited because of her marriage to an Italian singer, seeks both revenge and an ascension to the title (and the associated lands and title) for himself.
Guinness is great as an octet of often ridiculous nobles, while Dennis Price plays protagonist Louis with the right mix of snobbishness and gentility. The murders are often quite funny, and it's difficult to feel much sympathy for any of the D'Ascoynes. Louis also finds himself caught between two love interests -- manipulative and scheming Sibella, a friend since childhood, and the prim and proper Edith, widow of one of the more haplessly sympathetic D'Ascoynes. It's all a very funny and sometimes extraordinarily cynical and bleak look at the British class system. Highly recommended.
The Ladykillers: written by William Rose and Jimmy O'Connor; directed by Alexander Mackendrick; starring Alec Guinness (Professor Marcus), Katie Johnson (Mrs. Wilberforce), Cecil Parker (Claude (a.k.a. 'Major Courtney')), Herbert Lom (Louis (a.k.a. 'Mr. Harvey')), Peter Sellers (Harry (a.k.a. 'Mr. Robinson)), Danny Green (One-Round (a.k.a. 'Mr. Lawson')), and Jack Warner (The Superintendent) (1955): Oddly charming and gentle black comedy from England's Ealing Studios, the standard-bearer for black film comedy from the late 1940's through to the early 1960's. The body count is high, but it's hard to argue with the choice of victims.
Alec Guinness, sporting some pretty crazy fake teeth, plays Professor Marcus, the ringleader and chief planner for a quintet of thieves planning a big heist. Their plan hinges on Marcus taking rooms at the house of a deceptively lovable old lady (Mrs. Wilberforce, played wonderfully by Katie Johnson) for reasons I'll let the movie show you.
Guinness and his fellow actors -- including a young Peter Sellers and his police nemesis from the later Pink Panther films, Herbert Lom -- are terrific as their plan goes increasingly awry. Mrs. Wilberforce's ability to sow chaos wherever she goes without ever being affected by it herself repeatedly screws up the gang's plans. And their own somewhat English politeness makes the whole problem of eliminating Mrs. Wilberforce into an increasingly elaborate series of attempts and apologies.
The Coen Brothers remade The Ladykillers in 2004. It's not as bad a movie as some critics said, though it's also nowhere near the film that the original was. Alec Guinness trumps Tom Hanks. And the Coens didn't have Peter Sellers around to do uncredited work voicing Mrs. Wilberforce's two maddening parrots and a cockatoo. Highly recommended.