Claudia, recovering from cancer and sharing custody of her 12-year-old son Rhys, works as a primary school nurse and struggles to find meaning in her life. She tries in vain to help Imogen, a little girl she fears is being mistreated at home, but when she stumbles upon a search for five-year-old Emily Winter, who's gone missing from the playground on her street, Claudia is inescapably drawn to Emily's parents Owen and Sabine. As Claudia's obsession with the case grows, she forges a relationship with mysterious George, an English teacher at her school and finds herself in the midst of a deepening mystery.

Claudia sees George turn up for his class as usual and is horrified that he hasn't been arrested. Ejected from the Winter house for giving them false hope, she refuses to believe that George could be innocent and desperately starts digging into his past, choosing to ignore her increasing unease about her son's strange behaviour. Claudia learns from Joanne's wheelchair-bound son Simon that Joanne may have been the last to see Emily alive. At the same time, she discovers that George was involved in another death, and is convinced that he really is the culprit. A confrontation uncovers the truth and Claudia realises the damage she has done — but not before the media announce a suspect has been arrested for the murder of Emily.