Life in Solby is nice and peaceful until one day Mitcho and Sebastian find a message in a bottle by the harbour. The bottle is from the missing mayor of Solby with a message that he is on a mysterious island and has made a great discovery. Now they must embark on a perilous journey to help save the mayor and bring him home, and in the process they uncover something that will bring great pleasure to the city of Solby – a giant pear.

The Olsen-Gang must carry out an entrusted task for the Prime Minister's Office itself: H.C. Andersen's original quill must be stolen from the Danish Export Museum, supposedly for the Kingdom's safety and good reputation. But Hallandsen has again taken Egon's ass. There is nothing less than the Danish national feeling, Egon's honor and 30 million at stake. But Egon has a plan - he needs a drill, a glass of honey, a bottle of organic prune juice and a good pile of dead rats. Christiansborg is put on the other end, the metro is delayed more than usual and the Queen's guards suddenly dance the cancan.