Nazanin Zaghari-Ratcliffe pictured with her daughter (Image: Free Nazanin campaign/AFP via Getty)

BBC One is set to broadcast the first episode of its new factual drama, Prisoner 951, on Sunday evening.

The four-part series is based on the real-life ordeal of Nazanin Zaghari-Ratcliffe, a 47-year-old British-Iranian citizen who was imprisoned and held hostage by the Iranian state for six years.

Her husband, Richard Ratcliffe, tirelessly campaigned for her release and justice.

In 2016, Nazanin travelled to Iran with her then 22-month-old daughter Gabriella to visit family, only to be arrested and held for nearly six years on suspicion of espionage.

Richard, thousands of miles away in London, refused to remain silent and launched a campaign to secure Nazanin's freedom, which included a

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