Abby Grant is the main characters in the series. She is the leader of the survivors. She's a woman who – having lost her husband David to the virus – is determined to find her missing son Peter, who she insists throughout the series has survived the pandemic because she did, and thinks he's inherited some immunity.
She is very concerned about Peter's well-being, as he was recovering from leukaemia and was enjoying an outdoor adventure holiday at Castle Crag Adventure Centre in the Peak District when the virus took hold. Abby has been told by Callum Brown, the last surviving instructor – and sole survivor – at Castle Crag, that Peter was one of the first boys to be taken ill and had been taken to hospital by another instructor named Phil Emerson. However, Abby failed to find Peter at the hospital and her son's present whereabouts currently remains unknown. Abby unites the series' first group, within which she strives to maintain peace and welcome new characters – as well as looking for any lead, no matter how small, that will one day reunite her with Peter. She is the only character to have survived the virus without immunity.
Kidnapped by masked gunmen at the end of the last series - Abby awakes in The Lab dazed and confused, unaware that her life is in danger. Abby's journey through this series sees her grow from a traumatised victim of the Lab's cruel experiments to a strong and resilient leader. However, her deeply held morality is set to be shaken, particularly in the light of discovering the details of Tom's past and what harbouring him means. She also acknowledges that the quest for her son must take a back seat to securing a future for her new family.