Lamb to the Slaughter — Margaret Carr

Emma felt indebted to Nat. It was he who had kept her sane that dreadful night when they lay trapped in the wreckage of the train together. Now he was in a wheelchair, unable to walk. That was whyshe had taken up the beautiful Lisa's offer of a job - she had to do what she could to help. Poor Emma. She was too trusting, too innocent by half. The perfect victim.