After seeing an ad in a magazine, Nana Miller abruptly leaves Paris for a week in Copenhagen, leaving her teenage daughter alone. Nana has barely arrived in the Danish capital when the entire country is thrown into turmoil: a mermaid has been found dead! Nana soon makes friends with Thyge, a quirky local who hosts a children's radio show, and together the two jump headlong into adventure. With the help of the Poodle Club, the pair are determined to get to the bottom of the mystery that has brought Denmark to a standstill.
