Making Waves - Miracle: Salvation Isle, #6

Glyn Webb had always fought for justice. He never backed down, even when fighting the leadership of his rookery of penguins. But when he and the rest of his town had been overrun and sold to one of the most dangerous countries in the world, he'd discovered he wasn't as brave as he'd once thought. Cayman Dahl had been trained from childhood to defend the fever of manta rays by his Alpha father. It hadn't been easy, but in the end, he'd thanked his father for making him an invisible killer.
He knew how to watch his enemy without ever being detected. It was this skill that had the Council turning to him since hunters had started taking shifters and selling them. When the Council sends him on what is basically a suicide mission, Cayman didn't hesitate, despite the odds of him setting any of those captives free. But when he scents his mate, Cayman is determined to free them all, even if it means his own death.