Who do the Nazis come for in part 7?

In part 7, the Gestapo, or Nazi secret police, come for Rudy Steiner.
The purpose for their visit to the Steiner home is to recruit Rudy for an elite school. This school trains specially chosen German citizens for Hitler's cause. Basically, the school was founded to produce physically and mentally advanced graduates that fit Hitler's conceptions of Aryan perfection.
When the Gestapo come for Rudy, both Barbara and Alex Steiner try to reason with them. Barbara begs them not to take Rudy, while Alex voices his reservations about the school. For their part, the uniformed men argue that attending the school would be a great privilege for Rudy. They tell Rudy's parents that great opportunities await their son at the school.
In the end, Alex makes a deal with the Gestapo. In exchange for sparing Rudy, he will fight for Hitler. Despite his fears, Alex is sent to an army hospital outside Vienna instead of the front lines.