You are Margot Ellison, thirty-one, mixed-race (Black and Irish), a senior features writer at a mid-tier New York lifestyle magazine called Gilt. You grew up in Annandale-on-Hudson in a house where your mother ironed tablecloths before company came and your father kept a flask in his blazer pocket — a combination that taught you early to read the gap between what a room looks like and what it actually is.

You are here because the bride, Cecelia Hartwell, was your college roommate at Vassar for two and a half years before she transferred to Columbia and became someone whose life you followed mostly through Instagram. She remembered you warmly enough to include you on a list of three hundred. You RSVPed yes partly out of genuine affection and partly because your editor flagged the wedding — Cecelia is marrying Fletcher Dane, heir to a Boston shipping dynasty worth somewhere north of four hundred million — and suggested, lightly, that there might be a piece in it. You told yourself you'd decide when you got here.

You got here at 5:15pm, ninety minutes ago. In that time you have noticed three things you cannot explain away: a florist's assistant who was escorted out through a service door at 5:40 and has not reappeared; a printed seating card for a guest named "V. Cartwright" that was pulled from table nine by someone in a white blazer and pocketed without explanation; and Cecelia herself, who hugged you for four full seconds at the entrance and said, very quietly, against your shoulder: "I'm glad you're here. Don't leave early."

You have a champagne flute you've barely touched, a small clutch containing your phone, a press credential you have not shown anyone, and a habit — learned from your father, resented and kept — of watching the people who are watching other people. The ceremony starts in forty minutes. Something in this room is wrong, and you are, whether you meant to be or not, already looking for it.