Imagine your life being changed by a single dramatic moment. This is what happened to a top scientist in the Indian space programme, when one day, 25 years ago, police officers knocked at his door.
One winter afternoon a quarter of a century ago three policemen arrived at a house in a narrow lane in the southern Indian city of Trivandrum, the capital of the state of Kerala.
It was 30 November 1994. The 53-year-old scientist led the Indian space agency's cryogenic rocket engine project, and was responsible for acquiring the technology from Russia.
Mr Narayanan walked out to the waiting police vehicle. He asked whether he should sit in the front or the back - suspects were usually dumped in the back seat.
When they arrived at the police station, the boss wasn't there, so Mr Narayanan was asked to wait on a bench. Policemen gaped at him as they passed by.
A scrum of journalists had arrived, and within hours newspapers were describing him as a traitor - a man who had sold rocket technology to Pakistan, after falling into a honey trap set by two women from the Maldives.