Jodie never wanted to come on the residential trip to the field centre. A loner at school, she's forced into a dormitory with other girls from her class who don't understand her and talk about her behind her back. Even though they're not trying to be mean, Jodie feels excluded and miserable, and eventually escapes out onto the salt marshes in search of a little dog she can hear barking in the distance. But the salt marshes are dangerous and Jodie gets trapped by the incoming tide. Stuck in the sucking mud, will anyone even notice that she's gone? And where is the little dog that keeps barking so mournfully?