Theodosia Throckmorton, a clever and shrewd girl of sorts, has the harrowing and busy work of nullifying curses in her father's museum, where the darkest spells abound.

Her hands are full enough when her mother returns from the tombs of Egypt, bringing countless cursed valuables and antiquities with her.

The Heart of Egypt is stolen, and Theo suspects someone from the British Museum and investigates, Henry tagging along without her consent.

Will and Henry bring help, and Theo is introduced to Lord Wigmere, head of the Antiquarian Society and The Brotherhood of Chosen Keepers, a group dedicated to nullifying curses.

Theo is also angry that Wigmere may suspect her mother of stealing the Heart of Egypt, as she works closely with Count Von Braggenchnot, head of the Serpents of Chaos who will do anything to rain plague and pestilence down on England.

She reaches into the pocket of her pinafore and throws sand from the tomb at Nigel, the left side of his face dissolving.

They return home, where Wigmere gives Theodosia a ring, and Theo becomes an official member of the Brotherhood of the Chosen Keepers.