The Three Investigators are a juvenile detective team living in the fictional coast town Rocky Beach in southern California (near Los Angeles) The main characters, Jupiter Jones, Pete Crenshaw and Bob Andrews, have their headquarters in a hidden old trailer. They solve any mysterious case without sparing any risks and dangers. Their strong points are careful investigation and incredible power of deduction.

The Three Investigators have been created by American journalist and author Robert Arthur. In Germany the series is re-named “Die drei ???” (The Three Question Marks) and has long become cult. While the books in America and the UK feature artistic wraparound covers, the German edition catches the reader’s eye by dark black covers. Irrespective of language and cover, readers of every age and nation appreciate the famous crime stories.

1964 the first book was published under the title "Alfred Hitchcock and The Three Investigators" in the USA. Robert Arthur knew Alfred Hitchcock well and decides to use his famous name to attract attention for his new series. (Since 2005 publisher’s in Germany stopped using the name “Hitchcock” for their series, as they were no longer licensed to do so.). Unfortunately, Robert Arthur died 1969 having written no more than 10 books and varying authors started to continue his work.

Also audio plays on the Three Investigators have gained cult status and are said to be the most successful audio series world-wide. Surprisingly, more than a half of the buyers in Germany already are grown-ups.

Since 1968 the Kosmos Verlag publishes branded books under the "Die drei ???" label and made it the most successful juvenile crime series in German speaking countries. After the original series had been discontinued in the USA, Kosmos resumed the series in 1993 with German authors, new crime cases and unceasingly high demands on quality. The awareness of the "Die drei ???" brand in Germany is still amazingly high. Kosmos releases an average of six new crime stories a year. By now, the number of books by German authors has long surpasses those written in the United States.