The Deptford Mice Almanack is a companion book to the Deptford Mice, Histories and Mouselets by Robin Jarvis.
The almanack is presented as though it were written by Gervase Brightkin, a red squirrel. There are entries for all the days of the year, and every major event in the main novels is given a date. Also, much of the folk lore and elaborate traditions of the mice, bats, squirrels and rats is recorded in the almanack.
Throughout the almanack, Gervase writes of his stay in Greenwich Park during the tenth year of Audrey Scuttle's reign as Starwife. He also travels to Fennywolde and Holeborn to ask William 'Twit' Scuttle and Arthur Brown to tell their stories.
While in Fennywolde, Gervase encounters Alison Sedge, the fieldmouse who was jealous of Audrey in The Crystal Prison. Seemingly driven mad because of the death of her love, Jenkin Nettle, she solemnly warns that Audrey will not be the Starwife for much longer and will know great loss.
At the end of the year, the Great Oak—in which the rat god Hobb was imprisoned by Ysabelle in the distant past— falls down because of heavy winds, and many of the grey squirrels in the park begin to whisper that it was Audrey's fault because she is not a squirrel but merely a mouse.
When the black squirrels Morella and her father Modequai arrive in Greenwich, they and the grey squirrels plot against Audrey, and finally storm into her chamber and oust her from office. Then they give the silver acorn to Morella and she takes the title of Starwife. Strangely enough, she bears a resemblance to Alison Sedge.
The almanack ends on this ominous note, opening up the possibility of a new Deptford Mice novel.