Lucy Jarrett is terrified. She's convinced that somebody is watching her, following her home from work and lurking in shadows. But when she looks, there's nobody there. The phone calls are real enough, even if the caller never speaks, although they never seem to happen when her husband is at home. She's struggling to make anybody believe her, but with the recent murder of another young woman, DI Tom Mariner must take Lucy's fears seriously.

However, that's not all that DI Mariner has to contend with. His team is stretched to the limits when Nina Silvero, the widow of a former police officer, is found brutally murdered in an attack that could hark back to her husband's past misdemeanours. Someone, it seems, is out for revenge...