Lockwood & Co. #3: The Hollow Boy by Jonathan Stroud

Lockwood, George, and Lucy are very busy hunting down ghosts; so busy that they rarely work together anymore. Lockwood decides to hire a new girl, Holly, to take care of the office and keep things organized. Lucy finds it hard to get along with her;  maybe it's just jealousy. Lucy is sensitive to hearing ghost talk, so she tries to actually communicate with them. She's able to safely communicate with a spirit the first time she tries, but it endangers everyone to the deadly ghost touch. Lockwood orders her to never try it again, but will she listen? The bigger story is that a major outbreak of ghosts has ravaged Chelsea over the past few weeks, and a number of people have died. All of the major agencies have been called to find the Source, where the hauntings started, and Lockwood & Co. are finally asked to join when things get really bad. However, once they discover how bad things are, they may wish they hadn't.

You don't need to read the previous two books to enjoy this one, but it would help to understand the background stories. This book reveals a little bit about Lockwood's past, and Holly's appearance changes the behavior of the main characters. Lucy thinks the boys are overly fond of Holly, and it hurts her feelings. The skull in a jar is a fun character. Lucy is the only person who can talk to him, and his comments range from helpful information to sarcastic comments about hoping everyone dies. The climax of the plot is suspenseful, as the Source is found. The author leaves some mysteries unsolved, and a huge surprise awaits on the last page!