In December 1984, a group of teenagers on a school trip from West Germany crossed the border into East Germany. When they returned, an East German defector was hiding under a seat on their bus. Sophie Hardach speaks to those involved 35 years on and revisits their incredible story. Plus: Jo Holdaway on the GM anti-virus drug that saved her daughter’s life

It began as a typical 1980s school trip: a group of teenagers piled on to a bus, Duran Duran were on the stereo and spirits were high. What happened next caused a sensation: it was part The Famous Five and part John le Carré thriller.

The teenagers were from Marburg in West Germany, crossing the border into East Germany. While they were there, they managed to evade their minders and hatched a plot to smuggle a young defector out of the country with them. It was a plan fraught with danger: leaving East Germany was a criminal offence and hundreds of people had been killed making the attempt.

The journalist Sophie Hardach returns to her hometown of Marburg to revisit the story and speak to those involved 35 years on. She describes to Anushka Asthana the impact it has had on their lives.

Also today: Jo Holdaway on the world-first GM virus treatment that saved her daughter’s life and offers hope for a solution to antibiotic resistance.