The ghost of Sherlock Holmes is dead, but who will solve his murder? The Great Detective's ghost has walked London's streets for an age, given shape by people's memories. Now someone's put a ceremonial dagger through his chest. But what's the motive? And who - or what - could kill a ghost? When policing London's supernatural underworld, eliminating the impossible is not an option. DI James Quill and his detectives have learnt this the hard way. Gifted with the Sight, they'll pursue a criminal genius - who'll lure them into a Sherlockian maze of clues and evidence. The team also have their own demons to fight. They've been to hell and back (literally), but now the unit is falling apart....