A deeply moving story of Sid the dog losing his beloved owner Sam, and finding a new kind of happy. Sid loves his best friend and owner, Sam. They share a happy life together, playing, snoozing, and meeting friends like Sophie and her mum in the park. Sid is sure that these good times will last forever, but he soon starts to notice that Sam isn't quite himself. One morning, Sid wakes up to find that Sam isn't there. Sid feels sad and lonely, but can Sophie help him be happy again?.