[2] In the film—which is narrated by Warren Burton—Wirt (Elijah Wood), his brother Gregory (Collin Dean), and Beatrice (Natasha Leggero), a bluebird, head to the big city in search of an arcane book of all known things, meeting a vegetable man along the way.

In a large forest simply called the "Unknown," Wirt and his brother Gregory walk with Beatrice (Natasha Leggero; later voiced by Melanie Lynskey in the miniseries),[2] a bluebird who has gained the ability to speak.

Crops reveals that they have arrived at the "big city," which turns out to be an old-fashioned small farm community in the middle of the cornfield.

As Wirt, Greg, and Beatrice attempt to escape without Crops, they are set upon by the giant animals, including an alligator, who start to devour the vegetable car.

As Wirt tries to fend them off, Greg jumps out of the car and wanders into the cornfield, where he finds a goose big enough for the group to ride.

[4] This proved unsuccessful as he felt it needed to be episodic, laying out plans for a full television series consisting of three seasons.

[3] The project was placed on the backburner when McHale was recruited as creative director for Pendleton Ward's Adventure Time, also a Cartoon Network production.

[3] Although it reused the main characters from the pilot, with Wood and Dean reprising their roles of Wirt and Greg, the premise of them searching for the Tome of the Unknown was abandoned and changed to a much simpler and flexible story of them getting lost and trying to find their way home, and was retitled Over the Garden Wall.

[6] Nick Cross, who worked as a background painter with layout designer Chris Tsirgiotis on Tome of the Unknown,[7] was hired as the art director for the series.

Róbert Kovács-Cohner of the Hungarian IGN gave it a high recommendation, calling the story beautiful as it occurs over the backgrounds.