After a long hiatus, the BBC's Prime Suspect returns with intriguingly up-to-the-minute subject matter and a fresh subtext: aging. As Helen Mirren's Jane Tennison nears retirement age and spars with younger detectives as well as her superiors, she must trace a pair of murders whose elusive trail leads her back to the Balkan civil war of a decade earlier. The long break after Prime Suspect 5 clearly served Mirren, and the franchise, well. The star turns in some of her most nuanced work on the series to date, while director Tom Hooper locates genuine creepiness in both hospital corridors and the Balkan countryside. Writer Peter Berry tones down the series' long-running propensity for slightly shrill identity politics, teasing out subtler social subtext that's completely embedded in plot and character. By broadening the scope of modern, multicultural Britain to include Bosnian refugees, Prime Suspect 6 widens the series' scope and provides some much-needed novelty. A close cousin of Stephen Frears' Dirty Pretty Things, the series explores the grey market of culturally invisible immigrant workers while also touching on the Islamic anxieties of the 21st century. A strong argument for the wisdom of British TV's willingness to let a series restore its creative juices, Prime Suspect 6 suggests that Mirren and company could provide infrequent but excellent entertainment for years to come.