Penny Cheerful, 25, athletic, educated and very pretty, her assistant Jake a great young man who can read minds and of course Nessi, her dapper office fairy who always knows everything that's going on.
These three very different characters are at the heart of their investigations at what is now London's best-known and most secretive detective agency.
By chance, they slip into the world of demons, vampires and other creatures, where they solve cases and make new friends as well as plenty of unbelievable things.