Unreal City (Three Cities) (Volume 1)

What if you didn't have to die? What if you could live again and walk like a wolf among sheep, not caring about the fate of the people you kill? Would you take that gift if offered it? 
London 1925. This is a city only half recovered from the losses and anguish of the First World War. Museums are now opening again but the Defence of the Realm Act is still in force. Haunted by the army of the young dead, London vibrates to the the Cult of Youth. Faces turn from pain and memory and seek immediate pleasures in dance tunes and cocktail bars. 
An Ottoman dagger comes up for auction. It is made from a rare metal fallen from the sky and it is one of the few things that can kill vampires. These are the Clan of the Secondborn, imaginary creatures created from lust and hunger; monsters that do not live and do not die, incomplete, ravaged by an overpowering hunger for life.
Tasmin Fitzgerald, a well bred dealer in antiques, has always been a dutiful daughter but when her sister dies in mysterious circumstances, she decides life is too short and she is going to live for herself from then on. 
She falls for a sinister French poet who asks her to buy the Ottoman dagger for him.  Before long, she finds herself pitted against the Breton private detective Christian Le Cozh and an Austrian professor who want the dagger to use it against the vampires. 
At first she doesn't know who to believe, but soon Tasmin must decide whose side she's on, that of life, or that of undeath.