Clockwork Prince by Cassandra Clare

Set in Victorian London, Clockwork Prince, the second installment in Cassandra Clare's Infernal Devices trilogy, follows the orphaned shape-shifter Tessa Gray as she continues to work with the Shadowhunters Will Herondale and Jem Carstairs to combat the Magister's escalating war. Their investigation into the Magister's past and his clockwork army reveals deeply personal motivations rooted in tragedy and betrayal. As the trio navigates perilous journeys and uncovers shocking secrets about Tessa's origins, they face internal conflicts and shifting relationships, particularly concerning their growing feelings for one another. Amidst political intrigue within the Shadowhunter Council and encounters with Downworlders, they strive to uncover the traitor in their midst while battling both external threats and their own emotional turmoil.