Piccadilly, Thomas, and Arthur go to the power station hoping that they can vanquish Jupiter by using Audrey's mousebrass charm, which is what worked last time. Lured to his master's base, the Deptford Power Station, Morgan is confused and horrified when all his rats are immediately murdered by Jupiter on their arrival. But Jupiter appears to Morgan and once again ensnares him into his service. The city rats, now led by Jupiter's former lieutenant Morgan (who survived his fall into the sewer water at the end of the first book), prepare to go to Deptford and slaughter all the mice there. The Deptford mice soon reach the horrifying conclusion that the spirit of Jupiter has returned to seek revenge by smothering the world in eternal winter, and they have no idea how to defeat him this time as he is already dead. Several troubling events begin to occur: the psychic bats leave the house's attic, the Starwife's magical Starglass is stolen, and there are reports of a bloodthirsty rat army growing in the city.

The Brown siblings, Arthur and Audrey, have returned from their disastrous stay in Fennywolde where, to prevent her being hanged as a witch, the latter was married to Twit. It is winter and Yule festivities are underway in the Skirtings, the mouse community of the old empty house in Deptford. The book continues the story of the young house mouse Audrey and her friends as they attempt to banish the spirit of the evil cat Jupiter once and for all. In 2002, it was published by SeaStar Books in the United States. It is the third book in The Deptford Mice trilogy, first published in the United Kingdom in 1990 by Macdonald & Company, London. The Final Reckoning is a dark fantasy novel for children by British author Robin Jarvis.

The Alchymist's Cat by Robin Jarvis