The Imitation Game
Enigma, and the room full of people it actually took to break it.
A Christmas Story
A decoder pin, a Caesar wheel, and the best joke ever made about a secret message.
National Treasure
An Ottendorf cipher on the Declaration of Independence, which is a book cipher wearing a hat.
The Goonies
A map, a riddle and a treasure hunt, which is a capture the flag with better lighting.
Windtalkers
Navajo code talkers in the Pacific, where a submarine was called an iron fish.
The Lord of the Rings
The beacons of Gondor: one single piece of information, sent hundreds of miles in minutes.
Sherlock Holmes and the Dancing Men
Stick figures broken by counting letters. Read the story, it is better than any film of it.
Contact
A message from space that opens with prime numbers, because counting is the same everywhere.