The Only Branch on the Family Tree

It’s always been Gemma and her mum – just the two of them. As close as best friends. But while researching a class project about family, Gemma makes a life-changing discovery. Her nan is not dead, like Mum told her, but alive and well and living close by.
Gemma now has huge question marks hanging over her. Why would Mum lie about this? What is her nan like? And what would happen if Gemma tried to find her?