In the opening episode we meet the Rees family, who is still processing the loss of beloved son and brother, Liam, when a mysterious stranger contacts the family, threatening to turn their world upside down once again. Although siblings Jamie and Megan are open to having the stranger in their lives, their protective older brother Will is suspicious of his intentions. Meanwhile, Megan is preparing to marry Gethin, but is she truly ready to settle down? Christine, the mother of the Rees family, is still fiercely devoted to her now grown children, and her caring nature carries into her career as a social worker. As client Kayla confides in her about struggling to cope during her pregnancy, Christine shares her own empty nest worries with colleague Beth. When she finds out about the stranger, she calls up old friend Kate to get intel on his background. It seems like she knows more than she's letting on, which leads to divided feelings and loyalties. What is Christine hiding from her family?