Dive into another exciting magical adventure for girls – will you answer the call of Silver Dolphins? It's the Spring holidays and there's a surprise visit from Cai's parents from Australia. But they've got unwelcome news – Antonia is devastated to learn that best friend Cai might be emigrating to Australia or moving back to the city.Cai faces an impossible choice: does he move to the city so he can still visit Antonia but give up being a Silver Dolphin or does he learn to answer the call in Australia without his best friend? Meanwhile a minke whale keeps getting stranded in the estuary. Antonia and Cai join forces with the local fishermen and the coast guard to try to save the whale but it keeps returning. Can there be another reason for its strange behaviour? And could this really be the end of Silver Dolphins for Cai?