Clockwork Angel by Cassandra Claire is book one in the prequel series the Infernal Devices based before the Mortal Instruments series began.
When 16 year old Tessa Gray crosses the ocean to England in hope of finding her brother. The time is the reign of Queen Victoria and something terrifying is awaiting for her in the London’s downworld, where vampires, warlocks and other supernatural folk stalk the gas-lit streets. Only the Shadowhunters, Nephilim warriors dedicated to ridding the world of demons, in order to keep the peace among the human world.
When she arrives in London, she is kidnapped by the mysterious Dark Sisters, who are members of a secret organisation called the Pandemonium Club; Tessa soon learns that she herself is a Downworlder with a rare ability. The ability to transform at will, into another person. The Magister, the shadowy figure that runs the Club, will stop at nothing to claim Tessa’s power for his own.
Tessa takes refuge with the Shadowhunters of the London Institute, who swear to find her brother if she will use her new found power to help them. She soon finds herself fascinated by and torn between two best friends; Jem, whose fragile beauty hides a deadly secret, and blue-eyed Will, whose caustic wit and volatile moods keep everyone in his life at arms length… everyone, that is, but Tessa.
As their search draws them deep into the heart of an evil dark plot that threatens to destroy the Shadowhunters, Tessa realizes that she may need to choose between saving her brother and helping her new friends save the world... and that love may be the most dangerous magic of all.
This book is spectacular, with everything I'd wanted in the TMI series and more. The magic and mysteries are compelling and Victorian London is a fantastic backdrop to this steam-punk tale about a girl who discovers she has incredible powers...and an incredible past. Tessa is a vibrant, fascinating heroine and all the secondary characters, including Will and Jem and Charlotte, are engaging and sympathetic. I thought this book was much more mature than the TMI series, so I'm very much looking forward to reading the next two Infernal Devices instalments.