One of the things in the book that Frieda makes reference to is related to one of the tattoos she sees on Hannah’s skin. She thinks that the tattoo refers to the myth of Persephone and the seeds of pomegranate. Demeter and Zeus had a beautiful daughter named Persephone. Demeter loved Persephone very much and wanted to keep her near always. Hades, who was God of the Underworld, fell in love with Persephone and wanted to marry her, but Demeter refused to allow it. Zeus saw how unhappy this made Demeter and Persephone, so he ruled that Persephone should live with Hades in the dark Underworld for three months of the year and nine months above in the sunlight. Demeter was overjoyed to have Persephone back, but her happiness did not last. Zeus found out that Persephone has sucked on some pomegranate seeds while down in the Underworld. This meant that Persephone had to go back. Because the plants had all died, people did not have enough food. Therefore Zeus decided that Persephone should come home. There was one condition- she could not have had anything to eat or drink while she was in the Underworld. Ever after, there was a winter for three months each year.
We know that Frieda is keen on the underground rivers in London, and she finds out that Hannah was once also interested in the River Effra, which is an underground river. The River Effra is a converted river or former large stream in south London, mainly underground — due to its history and the pressing need in the late Victorian era for a surface water drainage system its contours have been used for a combined sewer similar to the Walbrook, draining for example much of the historic broadly defined areas of Peckham and Brixton.