The third book in the Infernal Devices Series, CLOCKWORK PRINCESS continues where Clockwork Prince left off. The whereabouts of Mortaim, otherwise know as the Magister, is still unknown. The London Institute residents are trying to gain support of the Clave and find him before he strikes again.

Will discovers that Jem is taking large doses of the Yin Fen to keep him strong for Tessa, but also killing him faster. He travels through the Downworlders to buy more, only to find that it is all gone, someone has bought it all up.

When Jessamine Lovelace is brought back to the London Institute from Silent City, they are attacked by automatons in the courtyard. When Will sees Jessamine comes toward him, she says that the Magister is in Irdis before she dies of a stab wound that pierced her heart. Cecily Herondale, Will's sister figures out that Jessamine is referring to Cedair Idris, a mountain near their home land in Whales. Its when Jem comes walking back into the courtyard of the Institute do they realize that Tessa has been taken.

Jem's health takes a drastic turn after he collapses on the Institute steps. When Jem is able to speak, he tells Will to rescue Tessa since he is too ill to go himself. Will finds Tessa in Cedair Idris, and rushed to her without thinking get himself trapped with her. Magnus Banes arrived to get them out of their prison and meet up with the others. As the automatons fill into the cavern within the mountain, Tessa uses her clockwork angel necklace to save those she loves.

Once back at the Institute, the reality of the events have hit hard. Jessamine is gone, Jem is gone, Henry's injury is permanent. Will needs to figure out a way to be a shadowhunter without Jem. Now that Tessa knows exactly what she is, she knows she can not replace Jem in Will's heart, but hopes that she can be Tessa for him and fill part of that void in his heart that Jem held.

As the story ends with Tessa at the Blackfriars Bridge in London, when she is well over a century in age. She is contemplating her long life when she meets someone from her past she though was gone to her.

Cassandra Clare's Infernal Devices series is one of the best series I have read. The story lines are gripping and hold your interest page by page. Her world of Tessa, Will, and Jem is fascinating! If you haven't read her Infernal Devices or Mortal Instruments Series, you need to! They are both excellent!