DI Kate Ashurst and DS Emma Scribbins investigate the mysterious death of affluent party girl Nikki Pengelly. Her distraught fiancé Ralph blames Nikki's besotted ex-husband Gavin but the investigation leads the detectives to the Applejacks dating agency, run by Redmond Appleby and his wife Maxine and a back-to-school disco. Then Ralph's bitter ex-girlfriend Hazel goes missing.
