** SPOILERS **
"She is a disease!" rasps Sebastian (Cosmo Jarvis), the hapless, beguiled groundskeeper, when he fingers his lover Katherine (Florence Pugh) as a murderess most foul at the conclusion of director William Oldroyd's maliciously spellbinding Lady MacBeth. Based upon the novel "Lady Macbeth of the Mtsensk District" by Nikolai Leskov and not something some guy named Shakespeare wrote, Katherine, the "heroine" of this sordid, bloody tale of murder in the manor is Lady MacBeth in kindred spirit only. Kindred spirit by means of body count.
Pugh delivers an increasingly unnerving and mesmerizing performance as Katherine, who is sold along with her parcel of land to a loveless marriage. Her sole duty in this arrangement is to provide an heir; otherwise she can shut up and be part of the furniture for all anyone cares. The extent of her new husband Alexander's (Paul Hilton) willingness to consummate their marriage is to make Katherine disrobe and then turn and face the wall like she's in the shack of the Blair Witch. Then he hits the hay, apparently satisfied.
Katherine, however, is not satisfied by her exceedingly vacuous life of being wrenched into a corset and then sitting silently for hours in an empty house in Northern England. She yearns to make her own decisions and do what she wants. She has simple desires: a little sex, for starters. Oh, and to be rid of her husband and his cruel, domineering father Boris (Christopher Fairbank), who also hate each other. When both men depart on separate business trips, Katherine decides she rather likes being the sole lady of the manor, and starts laying down plans to make this arrangement permanent. Katherine's behavior unfolds haphazardly and with real malevolence she feels is justified, regardless.
Sebastian the groundskeeper thinks he's rather cleverly seduced Lady Katherine when she starts taking him to bed every night, but the poor sod is in way over his head. When Boris returns from his business trip, having heard all about Katherine spreading her legs for the hired help, he beats and imprisons Sebastian. Katherine has never seen a Treehouse of Horror episode of The Simpsons, but her revenge would fit right into any episode when she decides to start killing to eliminate her impediments. By the time Katherine's done, her body count is very impressive: two men, a child, and even a horse. The horse was especially hilarious; Katherine had never shot a rife before, and the kickback flings her backwards like she's a cartoon character.
All's well that ends well for Katherine. It's quite a body count for a bewitchingly ruthless young lady. Thing's don't go quite as well for Sebastian, who is racked with guilt and has the temerity to betray Katherine. His reward for confessing is being hauled off to the hoosegow, along with "his accomplice" Anna (Naomi Ackie), the hapless maid who goes mute from all ghastly murder she's had to clean up after. Poor Anna; she's the most befuddled domestic servant in a movie since Harry Osborn's butler in Sam Raimi's Spider-Man trilogy: "I've seen a lot of strange things in this house, sir!"