The Secret Speech by Tom Rob Smith (2009) Grand Central Publishing

A follow-up to Child 44, Stalin is dead and those struggling for power will use any means necessary to replace him.  Khrushchev writes a secret speech indicting Stalin as a corrupt tyrant, promising change in the Soviet Union.  Leo Demidov has to deal with the consequences of what he has done before.  He and his wife are raising two girls they rescued, but at the cost of the death of the girl's parents.  And someone is intent on vengeance against them all.