The Aquatilis Bestia Enigma

A young couple are killed in a car crash in Inverness Scotland. A Mermaid leaves her labyrinth heading for Sandwood Bay with a Merchild she has borne with a human she rescued. The human now married to a woman who cannot have children seeks to find the Mermaid and finds her and a son unbeknown to him. They adopt it. The boy has a web hand and foot. A man arrives with a boy with similar features. He is there to find who killed the couple and at the same time to find the mysterious Aquatilis Bestia. Two other men arrive seeking the beast and the $2m award when they find and photo it. Does it exist? Can it be found? Will it finally reveal Scotland's longest most outstanding mystery?