Inside a dimly lit club deep within sunkissed Greece, the cunning, dashing, and all-around brave secret agent Aubrey Argylle (Henry Cavill) is putting the moves (literally and figuratively) on the terrorist LaGrange (Dua Lipa), a member of an evil spy organization known as the Division. Suddenly, she reveals his cover’s been blown. Attempting to pursue Lagrange, Argylle is devastated to see a member of his team, the master tech whiz Keira (Ariana Debose), has been seemingly fatally shot. Ordered by his superior, Fowler (Richard E. Grant) to continue pursuit, Argylle finally gains the upper hand thanks to his trusty companion, Wyatt (John Cena). But things take a turn for the worse when LaGrange reveals that Fowler is secretly the head of the Division as well as the good guys. LaGrange kills herself, Argylle and Wyatt cut communication with Fowler, and wonder what their next move will be.
In the first of many rug pulls within “Argylle,” it’s revealed the incident was just the fictional narrative of Book 4 of the “Argylle” novel series, written by the successful author Elly Conway (Bryce Dallas Howard), a woman who turned to writing after a debilitating ice skating accident. Despite being notably single (save for her cat, Alfie), Elly is self-described as being in a relationship with her work, turning down a date so she can work on Book 5. Upon finishing the manuscript, Elly wakes up to see that her mother, Ruth (Catherine O’Hara), has already read it, and is unsatisfied with the book’s “cop-out” ending as only a mother could be. Promising mom that she’ll meet up with her for the weekend and hash out a new final chapter, Elly boards an Amtrak to travel home, given her fear of flying.
On board she’s pestered by an insistent “fan” of her books, Aidan (Sam Rockwell), who soon claims he’s a real spy and says she’s in danger. Elly is suddenly attacked by numerous assassins and is only able to escape thanks to Aidan’s help as the duo parachute off the train.