Promising start to this UK thriller

This is a UK based thriller which makes a refreshing change from the usual US setting. In the prologue we are introduced to a young girl who is told to stay in her room by her father who is acting strangely. In the next chapter, 20 years in to the future we are introduced to Georgia who makes courtroom sketches and its not clear if she is the girl from the prologue. She keeps seeing a little boy who no one else can see... This was a really promising start and you want to know what will happen next and what happened to the little girl at the beginning.