Mysterious things are happening at The Ghost Detectives! In the middle of the night, the Yellow Castle begins to shake, and Grandpa Nikodemus can be heard talking to someone invisible. Elsa and Kalle sense that something is wrong. Could it be a ghost that Grandpa is speaking to?

The next morning, he has disappeared without a trace, and at the same time, the newspaper warns that the Trix volcano is about to erupt. Where is Grandpa, and what is he up to? The Ghost Detectives have a new case to solve, and this time Elsa and Kalle’s own grandfather is in danger!

The Ghost Detectives and the Case of the Lost Treasure is the seventh installment in Kristina Ohlsson’s spine-tingling, humorous and clever series for the younger readers. Moa Wallin is the illustrator behind the vibrant and atmospheric images.