Istina - Raabe Melani

During a business trip to South America, a wealthy businessman Philip Petersen disappeared without a trace. His wife, zara, had been waiting for at least some news about him for seven years. One day she received a call from the Ministry of Foreign Affairs and reported that her husband is alive and returning to his native Hamburg. She's very excited, she's all a clump of nerves. How will they meet? What happens next? Where has Philip been all these years?
... A large delegation descends on the plane ramp. She looks hard at her face. But among them she does not see her husband. A stranger is led to her. And zara realizes that it's not Philip.
Who is this stranger, what does he want? And why is he threatening her?