童年的约定In the exciting fourth season, we fast-forward six years, discovering that Nikki (Esther Smith) and Jason (Rafe Spall) are experienced adopters having built a lovely little nuclear family, enriched by an extraordinary support network. However, as their teenage daughter, Princess (Scarlett Rayner), starts to yearn for a connection with her birth mother, Nikki and Jason find themselves confronted with the ultimate test of their parenting skills.