Apparently not much; until Dirk Gently, self stylised private investigator, sets out to prove the fundamental interconnectedness of all things by solving a mysterious murder, assisting a mysterious professor, unraveling a mysterious mystery, and eating lots of pizza- not to mention saving the entire human race from extinction along the way (at no extra charge).
To find out more read this book (better still, buy it and read it)- or contact Dirk Gently's Holistic Detective Agency.
"A THUMPING GOOD DETECTIVE-GHOST-HORROR-WHO DUNNIT-TIME TRAVEL-ROMANTIC-MUSICAL-COMEDY-EPIC"- The Author
ISBN 0-330-30162-4