The Times BFI London Film Festival is hoping to set a world record by staging 50 simultaneous screenings to mark its 50th year.
Bafta-winner Kevin Macdonald directed The Last King of Scotland
Up to 10 different films will be shown at London cinemas, and at locations including Heathrow Airport, St Thomas's Hospital and Holloway prison.
The festival has contacted Guinness World Records in a bid to stage the largest surprise film screening.
The festival holds a Surprise Film Gala at the Odeon West End every year.
The 50 Screens event will take place on 29 October, with tickets costing £5.
"It's a great surprise when the lights go down, and everyone is sharing in the surprise together," said a spokeswoman for the festival.
The annual film festival opens on 18 October with the European premiere of The Last King of Scotland, starring Forest Whitaker as Idi Amin.
Highlights of the two-week festival include Dustin Hoffman and Emma Thompson in Stranger Than Fiction, Paul Verhoeven's World War II drama Black Book, and Tim Burton introducing a 3D version of The Nightmare Before Christmas.