From 1969 to the present, Jean has written five children's novels about a gang of three mice in New York City, led by the daredevilish Marvin, who prefers to be called "Merciless Marvin the Magnificent". His two cohorts in adventure are the scholarly Raymond("the Rat") and the sensitive Fats("the Fuse", although his birth name is revealed to be Dudley in the most recent story).Originally, the trio lived in the Bijou Theater, but Marvin led them in a semi-successful robbery of a cheese shop down the street, and they temporarily moved in there. At the start of the second story, they move into a dollhouse in the toy section of Macy's Department Store, and all subsequent adventures have either taken place or begun there. All titles of the gang's stories have been titled "The Great something-or-other", and take place in Manhattan(except for the fourth, which begins when the gang is accidentally sent to Vermont in a care package).

• The Great Cheese Conspiracy (1969)
• The Great Christmas Kidnaping Caper (1975)
• The Great Rescue Operation (1981)
• The Great Summer Camp Catastrophe (1992)
• The Great Googlestein(Guggenheim) Museum Mystery (2003)