"Hidden Evil" is a contemporary mystery. Inspector Claire Grainger, who is already disgusted with the amount of violent crime in London, suffers through a sudden traumatic event that makes her consider leaving the London Municipal Police. She is not fearful; she's just furious about all the "in your face" street evil she has to live with. "What kind of life is this?" she asks herself and her sometime work partner Martin Stanley. Meanwhile, a suspicious death in Hampstead appears connected to an art fraud scandal at a gallery on South Audley Street in London's West End. Inspector Grainger was put on temporary administrative duty and then on paid leave after the trauma. As she copes with its emotional and physical aftermath she taps into what she calls her "inner bulldog" and makes steady progress. But she is eager to return to active duty -- even though she is still struggling with her decision about her future. Soon, her superiors judge that she is ready for investigative work -- her first choice -- and they put her in charge of the case of the suspicious Hampstead death. Inspector Grainger is pleased to be back on the job but finds herself challenged by a different kind of evil that is more obscure and perplexing than the "blunt instrument" and "in your face" evil that she has dealt with in the past. She recruits Martin and others to help her attack the baffling complexities of the mystery surrounding the suspicious death.