Wealthy crime novelist Harlan Thrombey, portrayed by Christopher Plummer, gathers his family at his opulent mansion to celebrate his 85th birthday. However, the morning after the festivities, his housekeeper, Fran, played by Edi Patterson, stumbles upon a shocking scene: Harlan has been found dead, appearing to have taken his own life by slitting his throat. An intriguing twist emerges as private detective Benoit Blanc, skillfully portrayed by Daniel Craig, is hired anonymously to investigate the mysterious circumstances surrounding Harlan's demise.
As Blanc delves deeper into the case, he uncovers a web of family tensions and grievances. It becomes evident that Harlan had strained relationships with many of his relatives. For instance, he had threatened to expose his son-in-law Richard Drysdale, played by Don Johnson, for infidelity. Moreover, his daughter-in-law Joni (played by Toni Collette) had her allowance cut due to embezzlement, while Walt, his youngest son, was dismissed from the family publishing business. Most crucially, Harlan disinherited his lazy grandson Ransom Drysdale, a character brought to life by Chris Evans, solidifying the idea that every family member had something to gain from his death.
The investigation unfolds with a lineup of intriguing characters, including Linda Drysdale (played by Jamie Lee Curtis), the real estate mogul and Harlan's eldest daughter, alongside Megan "Meg" Thrombey (Katherine Langford), Harlan's college-student granddaughter, and Jacob Thrombey (Jaeden Martell), who grapples with controversial beliefs. Adding to the chaos are local law enforcement figures such as Detective Lieutenant Elliot and Officer Trooper Wagner.
Unbeknownst to Blanc, Marta Cabrera, Harlan's devoted nurse played by Ana de Armas, is intricately entwined in the mystery. After administering Harlan's medications, she unwittingly becomes key in unraveling the truth behind his death. In a misguided attempt to avoid suspicion, Harlan manipulated Marta into leaving the scene, ultimately leading to his tragic end.
Struggling to manage her integrity, Marta's inability to lie without feeling ill complicates matters further during her questioning by Blanc. Meanwhile, family members express their discontent when they learn Harlan bequeathed his entire fortune to Marta. Although tension rises, Ransom emerges as an unexpected ally, guiding her towards safety amid the turmoil.
The investigation thickens as evidence emerges of blackmail, propelling Marta and Ransom to uncover hidden truths about Harlan's death, including a critical toxicology report. As the narrative unfolds, the dark bonds within this family are laid bare. Ransom's unscrupulous actions include tampering with Marta's medication, an extension of his manipulation aims to claim Harlan's wealth.
Ultimately, the climactic scenes reveal a shocking confession from Ransom, sealed by a twist of fate as Marta enacts her clever deception. When the dust settles, she finds herself the owner of Harlan's mansion, witnessing the fractured Thrombey family from a distance, embodying both the tragedy and triumph that ensued from one man's demise.
