„The Christmas Adventure of Katla and Leo“ is about the adventures of the siblings, Katla and Leo, and their dads, Grím and Kára, in the run-up to Christmas. The family lights the four advent candles, shops for Christmas presents at Kringlan, and the children get presents in their shoes from 13 famous brothers. On St. Lucia's Day, they eat skate, and on Christmas Eve, Christmas dinner is at six o'clock, right after the bells ring on the radio. The siblings discover the secret of the Yule Lads and find out that Christmas is in danger. The story also involves earthquakes, a rescue mission and Grýla's attempt to learn how to use a smartphone. All of Hremma's stories feature diverse characters, and Kötlu and Leó's Christmas Adventure is no exception. The story reflects everyday diversity and uniquely Icelandic Christmas traditions.