As they search for their missing father near their Cornwall home, Sapphy and her brother Conor learn about their family's connection to the domains of air and of water.

The village of Pembrose seems to be under siege by the ghost of a pirate called Black Bart, and Minerva and her friends are determined to contact the ghost and convince him to perform a good deed so he can rest--but the real problem may be an escaped villain named Cain North.

Minerva, Thomasina, Ravi, and the dog, Pendragon, continue their search of Lizard Manor for the door that will lead them to the legendary City of Ravagers, where they hope to find pirate treasure as well as information that will illuminate Minerva's mysterious origins--but their search is complicated by the appearance of a nosy social worker who insists on inspecting the house.

Minerva, Ravi, and Thomasina find a message in a bottle, a cry for help from someone named Morgana, which has floated out of the Rowan Forest, a mysterious place supposedly protected by enchanted trees--but when the three friends set out to find Morgana they discover that it is the forest itself that is in danger.

When fourteen-year-old Itchingham "Itch" Lofte discovers a new radioactive element, he must use all of his wits and scientific knowledge to stop a top-secret government agency, his greedy teacher, and an evil corporation from getting hold of it.