[1] It tells the story of Bert Ljung from 7 November to 31 December the year he turns 12 during the autumn term in 5th grade at his school in Sweden.

The book cover depicts Bert lying sick in bed in his untidy room, while bacilli are seen in the air.

Lill-Erik and Åke celebrate their birthdays, while in December Bert's school class holds a Saint Lucy procession, and a floorball tournament.

She is taken away by the ambulance, and Bert hopes the temporary teacher will be a girl from the United States in a swimsuit, but instead it is a man named Håkan Kelinus.

On 31 December he closes with the lines "Tack och hej – leverpastej", which become the standard closing lines for the books Berts första, vidare and ytterligare betraktelser as well as the TV series, as well as becoming characteristic for the entire Bert Universe.