Ulf Blanck 
The Three ???, Aliens in Rocky Beach (drei Fragezeichen) [EPUB ebook] 

Rocky Beach is haunted!
Strange noises are heard from the wastewater pipes, as if by magic unusual circles appear in the corn field and water red as blood pours out of the fountain on the market square. The Three ??? are puzzled but they actually don´t believe in ghosts or extraterrestrial life. An uncanny investigation starts. Maybe ghosts do exist after all?
In Rocky Beach, California, live the three detectives: Justus Jonas, Peter Shaw and Bob Andrews. Together, they are The Three ??? and there is nothing they don’t take on!
The three friends witness exciting detective stories, solve puzzles no matter how tricky, and can always rely on each other.