A girl is assaulted in a park and the only witness is her young daughter. The police are certain they know who did it, but the girl cannot identify the man in an identity parade. Hardy sees her domineering mother-in-law and her ineffectual husband, but gets no help from either of them. It is only when Inspector Fleming arrives at his laboratory that the pieces begin to fall into place. Guest stars Rebecca Saire, Gary Watson, Mike Lucas and Gary Smith.