Writer and creator Joe Barton has written a seamless, thrilling, affecting drama that spans eight episodes and two countries and a seemingly huge cast of characters. “Giri/Haji” might seem like a B-grade toiler from its trailer, but it leaps, in my opinion, into classic screen thriller territory. Half, or perhaps even more, of the dialogue takes place in subtitled Japanese, which makes for a pungently immersive cultural experience as well. At heart, the story is the familiar script of good brother chasing bad brother, but around that central arc, which never feels in the slightest inevitable in terms of twists, coil skeins of richly character-driven subplots that all hook back into the mother lode. In raw terms, the plot is this: Kenzo, a driven Tokyo police detective (played with breathtaking authenticity by Takehiro Hera) is dispatched covertly to London to track down his gangster brother Yuto (just as brilliant a depiction by Yôsuke Kubozuka). Yuto was thought to be dead; now he may have killed a Yakuza in London and plunged the Tokyo underworld into carnage. In London, the cast expands to include an idiosyncratic policewoman, a drug addict, a tattooed Brit gang lord, Kenzo’s daughter … all of them leisurely drawn out with fleshed-out lives, even while the drama surges and wanes. The cinematography and music are superlative. Even each episode’s recap of past episodes, a gruff Japanese-inflected potpourri of reflections accompanied by hand-sketched stills, is a captivating element of a captivating cinematic treat. One of this year’s highlights.