World-famous detective Benoit Blanc heads to Greece to peel back the layers of a mystery surrounding a tech billionaire and his eclectic crew of friends. During the COVID-19 pandemic in May 2020, Miles Bron, the billionaire co-founder of the Manhattan technology company Alpha, decides to host a murder mystery weekend at his mansion, the Glass Onion, on his private island in Greece. He invites five friends: Alpha head scientist Lionel Toussaint, Connecticut governor Claire Debella, fashion designer Birdie Jay, men’s rights streamer Duke Cody, and fellow co-founder and ousted Alpha CEO Cassandra “Andi” Brand. Detective Benoit Blanc also has an invitation, and joins the group along with Birdie’s assistant Peg and Duke’s girlfriend Whiskey.

Upon arrival, Miles questions Blanc’s presence, but allows him to stay, assuming that another guest invited him as a joke. Blanc overhears Peg confront Miles over a PR statement he wants Birdie to release and sees Duke watch Whiskey flirting with Miles on a bed. Before dinner, Miles shows off the Mona Lisa that he has on loan from the Louvre and reveals that the Glass Onion is powered by “Klear”, a hydrogen-based alternative fuel that Alpha will launch in a week despite Lionel and Claire’s safety concerns.