Unlike Briggs' other films, which were adapted from his books, Ivor the Invisible was his first project to be conceived directly for the screen.

[1] One morning, a schoolboy named John awakes to find an invisible giant sitting at the foot of his bed.

Ivor can create music, and later at the playground he gives John an invisible seesaw ride in the park, before playing about with ducks.

Ivor creates a great deal of mischief at John's school, writing rude words on the chalkboard.

On the way home, Ivor incites the wrath of an angry mob after tampering with the Belisha beacons and pelican crossings.