A medical student at Cambridge finds a raven hatchling stunned on the grass outside his dormitory. Told at the pet shop that the bird will have to be put down, he buys a cage instead and takes it home. He names it Edgar, after Poe.

Edgar does not mimic. Edgar talks. He learns phrases, uses them in context, and one evening is found perched on a keyboard, pecking at the keys. Asked what he is doing, the raven answers: “Letter.”

Twenty years later, Nigel Carpenter is a neuroscientist who has never stopped asking what that bird understood. With Mary Taylor, a colleague from MIT, he begins a line of research no ethics committee would approve. They reprogram their own skin cells into stem cells, culture them into brain organoids carrying the speech and auditory regions of their own cortex, and introduce those organoids into raven embryos. Six eggs are selected. Four hatch. Two survive.

Sam and Sally look like any other raven. They are not. They learn English, then history, then the news, and they begin asking the kind of questions their makers cannot answer. Ravens live in the world humans have built. They have seen the flooded coastlines, the burning forests and the sickened flocks, and they arrive at a conclusion the scientists never taught them: the species responsible will not stop on its own.

Elsewhere, refineries are exploding, from Baytown, Texas to the Persian Gulf. In Scotland and the Netherlands, ornithologists are tracking flock behaviour that no model can account for, and one of them isolates a signal at a frequency the human ear cannot detect. And in Silicon Valley, the founder of an artificial intelligence company with a global platform is about to be shown something he will not be able to unsee.

What the scientists intended was a discovery. What they released was a messenger.