The Hollow Boy by Jonathan Stroud

As a supernatural outbreak baffles Scotland Yard and causes protests against the psychic agencies throughout London, Lockwood and Co. continue to demonstrate their effectiveness in exterminating spirits. Anthony is dashing, George insightful, and Lucy dynamic, while the skull in the jar utters sardonic advice from the sidelines. There is a new spirit of openness between the team now that Anthony has shared his childhood story, and Lucy is feeling more and more like her true home is at Portland Row. It comes as a great shock, then, when Lockwood and George introduce her to an annoyingly perky and hyper-efficient new assistant, Holly Munro. Meanwhile, there are reports of many new hauntings, including an old school where bloody handprints and a glowing boy are appearing. But ghosts seem to be the least of Lockwood and Co.'s concerns when a living assassin makes an attempt on Fittes's and Rotwell's lives. Can the team get past their interpersonal issues to save the day on all fronts? Danger abounds, tensions escalate, and new loyalties form in this third delightfully terrifying adventure