When twin brothers Trevor and Kyle Ritland were children, their father — a biologist — would tell them stories about a mythical creature that lived high in the misty mountains of Costa Rica: the golden toad. The toad was elusive, he told them — but for a few weeks every spring, hundreds of them would emerge from the shadows to mate, lighting up the dense forest like brilliant spots of fire. Until one day, the golden toad vanished — never to be seen again.

It’s mysteries like these that have drawn scores of researchers out of their labs and into the wild — tugging them to explore, to climb distant mountains, to venture into faraway forests and discover or rediscover a creature, a place, some new clue.

On this encore episode, we hear stories of those adventures. We talk with Trevor and Kyle about their quest to find out what happened to the golden toad — and what they ultimately discovered. We hear the epic tale of writer Kim Frank’s travels to India in search of wild Asian elephants. And we talk with conservation ecologist Ryan Almeida about how the global wildlife trade is affecting certain species and their habitats.