When Mona Gray is ten her father contracts a mysterious illness. His gradual withdrawal from everyday life marks a similar change in Mona, who removes herself from anything - or anyone - that might bring her happiness. Numbers provide a kind of solace, and help her make sense of the world: she counts words in her head, adds her steps, and multiplies people in the park against one another. When she becomes a maths teacher, Mona delights her pupils by encouraging them to find objects that take the form of numbers. But when 7-year-old Lisa appears with a zero that displays real turmoil, Mona knows that in order to help a person in pain, she needs to find a way to connect with the world she has been afraid of for so long.An Invisible Sign of my Own is a story about children and adults, and how we protect ourselves from the things we fear the most.