Neil Cross, you sneaky bastard. It seems the (relatively) lower key and detachment of episode 4 of Luther was the series writer/creator's clever way of leaving the audience even more shellshocked by the truly stunning developments in the series' penultimate installment. Initially Cross and new director Stefan Schwartz appear to be picking up on the more conventional note of the last episode, setting up a kidnapping-for-ransom story in rather expectedly grisly fashion (namely, a severed tongue--which, naturally, is just a warm-up for things to come). But unlike the aberration of episode 4, this Case of the Week follows what had been the modus operandi of Cross in the first three: the procedural plot as an entry point to further illuminate and dissect the characters and their relationships. But Cross even manages to surprise at this angle; by the midpoint the episode is no longer so much about the kidnapping as it is taking a hard look not at DCI John Luther (Idris Elba) but longtime colleague DCI Ian Reed (Steven Mackintosh). At first the greater emphasis strikes a bit odd given Reed's heretofore fairly background status, but in keeping with how intricately layered Cross has structured this series, the further exploration of Reed leads to explanations and motivations for some of his decisions in previous installments, not to mention sheds light on perhaps why he and Luther share such a strong bond in the first place.
So goes Cross and Schwartz's remarkable job of not only building the tension, but also gradually widening the scope and raising the dramatic stakes as the hour progresses. First Luther feels the stress of merely the Case of the Week and its compounding complications; then it's the ever-volatile relations with his colleagues on the force; then it's the continuing drama with wife Zoe (Indira Varma), which reaches a new crisis point; and by the truly wrenching dual climaxes, all these threads have organically converged into one incredibly difficult (to put it very mildly) situation for Luther and everyone in his orbit. It's a reflection of the harrowing emotional roller coaster of this episode--further intensified by the incredibly powerful performances by Elba, Mackintosh, and Varma--that Luther's weekly encounter with scary psycho Alice Morgan (Ruth Wilson) is actually the hour's quietest moment--but it's perhaps the most emblematic of the entire series, as it distills what clearly has always been Cross's central concern. As all these external forces and circumstances close in on Luther, the biggest challenge is not to his smarts or his skill or even his sanity, but to the very core of who he is: his driving faith in--despite all the emptiness and ugliness he regularly encounters--the existence of love in world. As a massive cliffhanger sets the stage for a full-circle finale that again finds him on a single-minded mission fueled by passion and rage, Luther's success--and salvation--wholly rests on the confirmation or denial of his defining belief.