The holiday home in Upper Bavaria is a magical place for siblings Tim and Rosalie. No matter what time of year they visit Lake Ammer with their parents, the next adventure seems to be waiting for them. During their summer vacation, Tim and Rosalie, along with their friends Lotta and Xaver, try to find out if a real witch actually lives in the mysterious house on the edge of town. After an autumn storm, they follow a creepy noise and rescue two injured animals. During the New Year's transition, the children learn from Xaver's grandmother about the mysterious Rauhnächte and discover a forgotten room with a special surprise. In the Easter holidays, the four little detectives test their sleuthing skills and attempt to decode a hidden message.