Finn McFee, an eleven-year-old boy in the Scottish fishing village of Stromhead, learns that his mother was a kind of selkie who could turn into a dolphin. Because of her, Finn has the ability to swim faster and hold his breath for longer than other humans. Finn befriends a pod of dolphins who live near Stromhead. When he learns that a supermarket in nearby is going to release thousands of balloons that could kill dolphins and other marine animals, he and the other local kids campaign to stop the release.
Song of the Dolphin Boy contains examples of:
- Call Reception Area: Finn's father has always strictly forbidden him from going in water, even a bathtub. When he and his classmate Charlie get in a fight, Charlie chases him to the harbour, and Finn, backing away, accidentally falls in. Amazed by how safe and comfortable he feels in the water, Finn swims out to sea.
- Friendly, Playful Dolphin: The first time Finn swims in the ocean, he meets a friendly dolphin who has Finn chase him, then take turns leaping out of the water.
- Graceful in Their Element: Finn is clumsy and awkward on land, but in the water he can swim as quickly and easily as a dolphin.
- Green Aesop: Don't release balloons over the sea. An animal might mistake them for jellyfish and die from eating them.
- Heel Realisation: When Charlie thinks he's killed Finn by chasing him into the harbour, he and his friends realise how badly they've treated him over the years. Finn tells them they can make up for it by helping him save the dolphins.
- Love at First Sight: Finn's father was singing on the beach when his mother heard him and swam ashore. They both fell in love instantly.
- Mess of Woe: After Finn's mother disappeared, his father stopped working, cleaning the house, or tending the garden. The inside of their cottage is very dark because weeds and filth have covered the windows. The day after he tells Finn that his mother was a selkie, Finn is surprised to see him hacking away at the weeds for the first time in years.
- Missing Mum: Finn's mother, Sylvie, went missing when he was two. There are rumours that his dad murdered her. Finn eventually learns that she was caught in a fisherman's net while in dolphin form. Her husband tried to free her, but he was too late.
- Parental Neglect: Ever since Sylvie disappeared, Finn's dad has spent most of his time sitting forlornly in a chair. He buys food and clothes but otherwise has mostly left Finn to raise himself. He does become more involved once he learns that Finn was in the ocean and tells him the truth about Sylvie.
- They Would Cut You Up: Finn's dad tells him, 'You be careful, son. A scientist gets hold of you, and there'll be experiments and examinations and nosy parkers and journalists from all over. Let's keep all this to ourselves, eh? Our secret.'
