Subscribe and review on Acast, Apple Podcasts, Soundcloud, Audioboom & Mixcloud. Join the discussion on Facebook and Twitter and email us at Scienceweekly@theguardian.com

Last week, the city of Salisbury was thrust into the spotlight when two people were found in critical condition in a local park. Details began to emerge that the man, in his late sixties, was a former Russian spy. The woman found in a comatose state beside him, his daughter. Speculation mounted that they were poisoned, but by what? And by whom?

This week, Britain’s prime minister Theresa May publicly named the nerve agent used in the attack as novichok. She also pointed to Russia as the likely culprit. So what do we know about novichok? And how confident can we be that it was the Russians who carried out this attack?

We hear from the Guardian’s Maya Wolfe-Robinson and Luke Harding about what happened in Salisbury. And host Ian Sample also speaks to Alastair Hay, a professor of environmental toxicology at the University of Leeds.

