Mumtaz Muhammed is a young female mouse who came from Kabul, Afghanistan in "The Baker Street Family". She is Olivia's favorite best friend other than Carmen Rodriguez, Ana Maria Fernandes, and Kate Brown. Like Olivia and her friends, she goes to to kindergarten at Basil of Baker Street Grammar School, but was educated by her father during her first three years in Afghanistan. She is also talented and has a tendency to speak Arabic.