In the second book, The Crystal Prison, it is revealed that she was rescued in a bad state by the squirrels who work for the Starwife. At the Greenwich Observatory, the Starwife's home, Audrey is given a medicine to heal Oswald who is dying of fever after returning from the sewers. However, Audrey is given the magic cure on the condition that she take Akkikuyu to Fennywolde, Twit's home, and stay there with Akkikuyu to live out the rest of her days, since all Akkikuyu remembers is dreaming of going to a sunny and happy place with Audrey before delivering her to Jupiter in the first story. After arriving in Fennywolde, Akkikuyu begins to win the hearts of the Fennywolde mice after saving two of the young fieldmice from a terrorizing barn owl, Mahooot. After Mahooot is defeated, the fieldmice can finally move into the field from the summer, safe in the knowledge the rat will keep them from harm. After being rejected by Audrey, Akkikuyu walks alone through a field one night with a sharp pain in one ear. Soon her ear tattoo, which is a face, begins to talk to her, animated by a spirit who calls himself Nicodemus. He says he is the spirit of the fields who needs to be saved from limbo in order to bring rain to the parched cornfields. He tells Akkikuyu that to free him, she will need to sacrifice a young female mouse without a mousebrass. Nicodemus suggests Audrey, since she lost hers in the battle with Jupiter. The rat is devastated at the idea of killing her mouse friend. Later, the murders in the fields are blamed on Audrey, whose straw dolly was given life by Nicodemus and had been strangling and killing young mice. The fieldmice call Audrey a witch, and she is about to be hung when Twit quickly marries her to prevent her from being killed. They are reluctantly married, but it is revealed that both Twit and Audrey need to be blessed for the marriage to be validated. Audrey's brother Arthur blesses Twit, but no one will bless Audrey. To save her, Akkikuyu quickly gives her blessing, sealing the marriage and saving Audrey from death. Nicodemus is enraged by Akkikuyu's treachery, but he still says there is another chance, for another young female mouse - Alison Sedge - has thrown away her mousebrass. Akkikuyu reluctantly lures Alison into a magic ring in which burns a fire she has to throw Alison in to. Before she has a chance to, Nicodemus reveals himself as Jupiter. At the mention of the name, Akkikuyu remembers everything perfectly, and then refuses to do anything for the evil spirit. Jupiter then explains that he needs a new body to be host for his spirit so he can live once more. Jupiter forces Akkikuyu to perform a spell against her will, and slowly she begins to transform into a ginger cat. Horrified, Akkikuyu shouts that she will never kill the mouse, and jumps into the fire, killing herself. Her final words are, "Akkikuyu tried so hard mouselet." Her words trail off as the flames take her.
Her remains are later buried in Fennywolde under the hawthorn around the still pool, the sun shining on her burial site. Audrey says, "it's all she ever wanted," in reference to the rat's desire to be somewhere happy with the sun shining. The still pool later becomes known as "the witch's water," and youngsters often cast offerings into it and beg for wishes. It is told that on particular summer evenings, the wishes do in fact come true.