Inside of his book, adventurous Harold can make anything come to life simply by drawing it. After he grows up and draws himself off the book's pages and into the physical world, Harold finds he has a lot to learn about real life – and that his trusty purple crayon may set off more hilarious hijinks than he thought possible. When the power of unlimited imagination falls into the wrong hands, it will take all of Harold and his friends' creativity to save both the real world and his own.

As the bubonic plague spreads through Italy, a group of nobles and servants retreats to a villa, where their lavish getaway quickly spirals into chaos.