Ballydog is a bad town on the road to nowhere. It's also home to Andrew, the kingpin of the local school gang; May an outcast for her strange ways and ability to communicate with animals; and Ewan, a newcomer, hiding out in Ballydog under the witness protection scheme. Now these three teenagers are under threat as a vast ancient creature marches along the seabed towards their town, intent on destroying it. Can they save Ballydog - and is it worth saving?