A gym employee in downtown Salisbury was among the first to notice the pair.
It was the afternoon of March 4, 2018. Freya Church was leaving work at Snap Fitness when she spotted a woman aged in her 30s and an older man sitting just a few metres away on a public bench. They appeared to be slipping in and out of consciousness, fitting and vomiting.
"I was particularly worried about her," Freya told The Telegraph. "She was slumped over on the man’s shoulder... He was gesturing at the sky, doing some kind of movements with his hands. He was looking up and his eyes were glazed."
That man was 66-year-old Sergei Skripal, a former Russian military spy turned double agent who'd worked with the UK's secret intelligence service, MI6.
Watch: The events have been captured in the SBS drama series, The Salisbury Poisonings.
The woman was his daughter, Yulia, who was visiting from Russia. She'd arrived in the southern English cathedral city the previous day.
On March 4, the pair went to a local pub together and shared lunch at a pizza restaurant, unaware that a lethal poison was coursing through their nervous system.
After collapsing on the pubic bench, Sergei and Yulia were rushed to hospital and placed in an induced coma. They survived. But in the coming weeks, the poison claimed other victims, forcing Salisbury into emergency lockdown as authorities scrambled to contain the invisible threat.
As explored in the new drama series, The Salisbury Poisonings (available to stream in Australia on SBS On Demand), the incident thrust the city into the middle of a tense crisis of national security and international diplomacy.
Here's the incredible true story behind the program.