Russia’s reach is long, its methods secret, and its vengeance coldly calculated. On March 4, 66-year-old Sergei Skripal and his 33-year-old daughter, Yulia, who was visiting him from Moscow, were found critically ill, slumped on a bench in the English city of Salisbury. The British government stated that the two had been poisoned by a nerve agent called Novichok, which causes respiratory and cardiac arrest.

Though both Yulia and her father, a former Russian military intelligence officer turned double agent, recovered after lengthy hospitalization and are reportedly in a safe house, their lives will never be the same. Sergei, who worked for British intelligence agency MI6, will need to assume a new identity and, most likely, undergo plastic surgery to minimize the risk of recognition.

Poisoning is a tricky means of assassination. Though it offers would-be assassins the advantages of secrecy and a long-lead getaway (and, indeed, the British government has no suspects in this case), many victims survive if they receive rapid and aggressive medical intervention.

Investigators later determined that the Novichok had been smeared on the front doorknob of the Skripal home, a new and creative twist in Russia’s poison playbook, but not without substantial risk: There is always the danger that the poisoner himself will be contaminated. The Skripal case is just the latest horrifying incident in a string of poisonings linked to Putin’s regime, including sinister soup and toxic tea.

In 2004, anti-Russian Ukrainian presidential candidate Viktor Yushchenko barely survived a soup tainted with TCCD, an ingredient in Agent Orange 170,000 times more poisonous than cyanide, which left his face horribly disfigured.

In 2012, Alexander Perepilichny, a Russian national living in the UK, was less fortunate. Apparently, instead of sorrel, his soup contained gelsemium, a rare plant found only in remote parts of China and loaded with toxins related to strychnine. He dropped dead while jogging.

The journalist Anna Politkovskaya, a vocal critic of Vladimir Putin, became dangerously ill in 2004 after drinking tea on an Aeroflot flight. She survived the poisoning only to be shot while holding bags of groceries in her Moscow apartment building elevator in 2006. That same year, in London, Putin critic Alexander Litvinenko drank some tea brimming with polonium-210, resulting in such high radiation levels that doctors waited a week before performing an autopsy in hazmat suits.

In 1921, the Soviets established their first laboratory — the Kamera — for the manufacture of poisons. Their goal was to develop odorless, tasteless and colorless poisons that victims could not detect when ingesting and which would leave no trace. Whenever a poison was detected in the corpse of a political activist, it would not be used again. For this reason, the Kamera constantly developed new poisons.

The Soviets tested the poisons on condemned prisoners, mostly political enemies. Recent events have shown that this laboratory did not disappear with communism in 1991 but still exists. According to Boris Volodarsky, a former Russian military-intelligence agent and author of the 2009 book, “The KGB’s Poison Factory,” Kamera doctors calculate a victim’s height, weight, eating habits and other information in order to select a poison. The optimal dose is one that will kill the target but, leaving no trace, result in a coroner’s verdict of death by natural or undetermined causes.

Though Novichok is only manufactured in Russia, Putin’s government has denied involvement in the Skripal poisoning and accused Britain of planting the nerve agent on the doorknob to besmirch Russia’s reputation. On May 23, Reuters released a video interview with Yulia. “My life has been turned upside down,” she said in Russian, appearing healthy except for the raw tracheotomy scar on her throat. “Our recovery has been slow and extremely painful.”

It is tempting to assume that the near-murder of Yulia a day after her arrival in Britain was not the result of bad timing but was, in fact, quite intentional. It sends a strong message to others contemplating treason: We won’t just kill you. We will also kill your children.

Eleanor Herman is the author of “The Royal Art of Poison: Filthy Palaces, Fatal Cosmetics, Deadly Medicine, and Murder Most Foul” (St. Martin’s Press), out now.