Tom and his elder sister Alex holiday in Florida with four cousins of similar age. They share a large beach house belonging to a scientific institute engaged in the study of dolphins. What Tom expected to be a quiet vacation turns into a perilous adventure entangled in a criminal intrigue. Tom soon discovers he can communicate with these fascinating mammals, in particular with Elwar. Will Tom’s new friend come to the rescue in moments of danger?

This charming children’s story about the friendship between a boy and a dolphin is complemented by encyclopedic notes on marine mammals. It is recommended for children interested in life below the waves and for grade school teachers engaged in the subject.