The Poison Belt is a science fiction novel by British writer Arthur Conan Doyle, the second book about Professor Challenger.

[2] Challenger sends telegrams asking his three companions from The Lost World— Edward Malone, Lord John Roxton, and Professor Summerlee— to join him at his home outside London, and instructs each of them to 'bring oxygen'.

In the course of his research into various phenomena, Challenger has predicted that the Earth is moving into a belt of poisonous ether which, based on its effect on the people of Sumatra earlier in the day, he expects to stifle humanity.

The five wait out the Earth's passage through the poison belt as they watch the world outside, human and animal, die and machines run amok.

After returning to Challenger's house, they discover that the effect of the ether is temporary, and the world reawakens with no knowledge that they have lost any time at all.