Sirens (2002)

Sarah Parish is a copper who likes to keep herself busy—she's holding down a tough job, hunting a twisted criminal who is repeatedly ravaging the women of London, and snogging her sister's man. She's living a full life rife with excitement and enticement, but this master of multitasking is about to get thrown off course in Sirens (2002). It seems that none other than the sister's boyfriend himself has become the top suspect in the case; now Sarah has to choose between passion, professionalism, and plain old family ties. Should she confess the details of her double life? Will she lose her sis forever? And what will become of her lover? Just when it looks like things can't get any tougher, new details and motives come to light that reveal the true nature of the crimes.