Ripper Street, Series 2 Finale, BBC One

Though greeted ambivalently when it made its debut at the end of 2012, Ripper Street has looked increasingly like TV's undervalued secret weapon as it has surged purposefully through this second series. Maybe the title was misjudged, suggesting it was just another gruesome and mist-shrouded Victorian murder mystery. Turns out it was much more than that.

Indeed, echoes of Jack the Ripper have been almost entirely absent as the series has taken the plunge into such factually-based issues as rent-boy networks and the Barings Bank crisis of 1890 (different only in scale from recent financial catastrophes), religious cults and the 1888 London match-girls strike. Mostly, Ripper Street mastermind Richard Warlow has been skilful enough to use his material as a canvas on which to impose the show's own characters and preoccupations rather than just rehashing a pile of history books (Matthew Macfadyen as DI Edmund Reid, pictured below).

The final two episodes were concerned with tying up several ongoing themes. There was the fall and redemption of Sergeant Bennet Drake (Jerome Flynn), who had been sent spinning into an existential void by the death of his wife Bella. He'd gone AWOL from his police job and his home, and we eventually found him skulking in the grimmest corners of Whitechapel lowlife, earning a crust by allowing himself to be tied to a post and punched in the face by all-comers. If he could stay conscious for long enough, he got paid. It was a bit like the Christopher Walken role in The Deer Hunter, where he became addicted to Russian roulette.

Long story short, thanks to the love of another good woman - in this case Rose, another of Long Susan's working girls - he came back to H Division's Whitechapel nick in time to assist in some comeuppance-delivery to the despicable DI Jedediah Shine, Limehouse's godfather of all bent coppers. Played with slavering, slit-eyed relish by Joseph Mawle, he took an indecent delight in either garrotting people or knocking lumps out of them in the boxing ring, though predictably it was Drake, rendered punch-proof by diligent practice, who left Shine dangling bloodily on the ropes. It was easy to sympathise with DI Reid (Matthew Macfadyen) as he kept bawling "Kill him!" at Drake - in an earlier episode Shine had, after all, been audaciously portrayed as the man who killed poor Joseph Merrick, the Elephant Man - but Drake has gone a bit Zen and we may not have seen the last of Shine's evil empire. Meanwhile Reid's bloodlust didn't play too well with his new girlfriend, Councillor Cobden (Leanne Best).We did, however, see Long Susan (MyAnna Buring, pictured above with Adam Rothenberg as Jackson) prise herself free from the nauseating embrace of slum landlord and all-round sleazebag Silas Duggan (an exceedingly unsavoury Frank Harper), while the arrival of Homer Jackson's brother Daniel (David Costabile) has brought a light breeze of comic relief to the frequently Stygian proceedings. Pleasing too is the show's continuing delight in archaic language, though subtitles might sometimes be useful. Macfadyen had some choice moments: "I feel there the opportunity to correct not solely the darkness of the world in which I serve but also that which abides in my own heart."

Above all, Ripper Street has successfully developed an array of complex characters who have become increasingly believable the more you learn about them, even if the plotting can become feverishly overheated. The tangled, combustible relationship between Long Susan and Jackson is a particular triumph. Encore!