Sirens (2002)

As London languishes in a punishing heatwave, the heat is turned up on the police force as they find themselves pursuing a vicious rapist in this crime thriller. The events take a terrible turn for female police officer Ali (Sarah Parish) when her sister's boyfriend is fingered as the prime suspect, leading to a conflict of interest as she has to decide whether to reveal her relationship to the accused and risk falling out with her sibling.