Grace was grandmother of Ryan Sinclair, who she took care of after his mother passed away. She worked as a chemotherapy nurse and through her job, she met cancer patient Graham O'Brien, whom she later married.
Grace and her husband would often take Ryan out to teach him to how to ride a bicycle, which was difficult for him because of his dyspraxia. Following one of these sessions, Grace, Graham and Ryan encountered a Gathering Coil on their train. It was there that she met police officer Yasmin Khan and the Thirteenth Doctor for the first time.
She helped the Doctor, Graham, Ryan and Yaz battle a Stenza warrior known as Tzim-Sha (or Tim Shaw as the Doctor called him) who came to Sheffield to locate and kill his selected target, Karl Wright. The Doctor and friends were successful in sending Tim Shaw away to his home planet, but it came at a cost; Grace was killed whilst destroying the Gathering Coil that was being used to damage the crane Ryan and the others were on, and fell to the ground from a great height. She died in Graham's arms, urging him not to be afraid without her.