Devil's Work — Margaret Yorke

When Alan Parker is suddenly made redundant, he can't bring himself to tell his wife. With time on his hands while secretly and desperately looking for a job, he meets a waif-like little girl, Tessa, and her lonely, widowed mother. Alan discovers he can confide in Louise, and feels protective towards her and her daughter.

But then Tessa disappears. Alan, once utterly respectable, is now unemployed and living a life of deception and adultery. To the police, he is the prime suspect of a hideous and sordid crime.