Mrs. Churchmouse was the wife of John Churchmouse, mother of Tim and Tess, mother-in-law of Mattimeo, and the grandmother of Martin II. She lived at Redwall Abbey after relocating from Saint Ninian's Church.
Though taking almost no role in the wars during the Summer of the Late Rose, she was one of the foremost characters who protected Redwall in the absence of Matthias during the Summer of the Golden Plain. After Slagar the Cruel and his vermin band took a number of children from the Abbey (including Tim and Tess), she was part of the original search party that went after the kidnappers. But she returned to Redwall with the news that Matthias, Jess, and Basil Stag Hare were continuing after them.
Later that summer, Mrs. Churchmouse and Cornflower surprised a number of invading birds by ringing the Abbey bells, only to be captured when they tried to escape into Redwall. General Ironbeak then used her, Cornflower, and Rollo to barter for the possession of the structure. The Redwallers traded captives to rescue them, after which Mrs. Churchmouse helped Cornflower, Sister May, and Constance 'haunt' the birds as the ghost of Martin the Warrior.
Besides aiding in the defense of Redwall during the Summer of the Golden Plain, she also acted as a foster parent to baby Rollo.