An ill-fated experiment with a peculiar porpoise - to try to teach a dolphin to speak English - will be explored in a new documentary.
Secrets Of The Dolphin House will examine the 1965 scheme by physicist and neuroscientist John Lilly, which saw a fully grown male bottle-nosed dolphin called Peter live in a flooded house with researcher Margaret Howe.
Lilly, who also examined the effects of LSD on the brain, wanted to see if the creature could learn to speak and understand the language but as the weeks went by it became increasingly aggressive and difficult to deal with.
BBC Four's channel editor, Cassian Harrison, said: "This promises to be an extraordinary film about our relationship with the animal world - shocking and revelatory by turns - and born from some truly unique archive material. It's a film only BBC Four could do."
The 50-minute programme will be broadcast later this year.
Executive producer Mark Hedgecoe said "This is the story of the most extraordinary experiment in the history of animal science. It combines our human yearning not to be alone in the universe with expanding new-age ideas about consciousness and intelligence. And what's so strange is that it's a story that has never been told before."