The Hollow Boy is the third book in the Lockwood & Co. series, an edge-of-the-seat adventure in which ghosts haunt England and can kill with a touch. Aquamarine is a lower middle grade summer story about a mermaid who becomes stranded in a water park’s swimming pool. And The Case of the Gypsy Good-bye is the sixth and final installment in the Enola Holmes series. (Very much my favorite book discovery of 2017 and destined to be reread at regular intervals.)