Darkness Does Not Come At Once by Glenn Bryant

Meike is seventeen and she uses a wheelchair. Already in life she's accepted that she'll always somehow be 'different'. But overnight, different becomes dangerous after the government announces disabled youngsters under the age of eighteen must spend the war in specially designated institutions.
Suddenly Meike is on the run in the rural lanes she calls home, bordering Berlin. It is 1939 and the whole of Germany, it seems, wants to fight the world.
Quietly, members of Meike's family distance themselves, but two unlikely allies stand by her. One is an elderly woman and a lifelong Catholic, forced to question her faith; the other is a fifteen-year-old boy Meike hardly knows. They begin a search for answers as they scramble to find Meike and, in a country they no longer recognise, themselves.