A Night Divided

Started reading this book tonight and I am hooked.  Set in Germany after WW II - Gerta, her mother and brother Fritz live in East Germany.  Her father defected to East Germany because he did not agree with the government.  Gerta misses her father and everyone longs to join him, but the Stasi watch every move they make.  Gerta's best friend Anna had to learn the hard way that the Stasi are people who need to be feared and they all have to be careful.  Then one day Gerta sees her father standing on the fall that separate East Germany from West Germany and he is acting strange.  She sees him again and he is making the same funny movements.  What does it mean?  What is her father trying to tell her?  In A Night Divided decisions can mean death but they could also mean freedom.