"Celebrating her forty-fifth birthday at her local pub, popular podcaster Alix Summers crosses paths with an unassuming woman called Josie Fair. Josie, it turns out, is also celebrating her forty-fifth birthday. They are, in fact, birthday twins. A few days later, Alix and Josie bump into each other again, this time outside Alix's children's school. Josie has been listening to Alix's podcasts and thinks she might be an interesting subject for her...

The group was left reeling after the shocking death of Danny at the hands of hostage-takers as the last season concluded. Now Adam, Harry, Ruth, Fiona and rising star Zafar set out to become even stronger in their battle to safeguard the nation.