Compared to other episodes of this entertaining detective series, "The Japanese Painting" is full of plot-holes. The criminal mastermind behind the whole operation, Ernst Levendahl (Jan Malmsjö) claims that his mansion is phone-proof, yet Gunvald (Mikael Persbrandt) manages to make a call back to base. And, given that the mansion was supposed to be impregnable, maintained 24/7 by armed guards, Beck (Peter Haber) and his fellow-officers find it extremely easy to get in. Likewise Gunvald, although handcuffed to a water- pipe and beaten by the guards, manages to escape free, beat one of the guards on the back of the head and steal the guard's pistol.
Yet such implausibilities do not really jar in an episode concentrating far more on characterization, especially the relationship between Beck and his long-time German police colleague Hans (Dieter Pfaff). The two of them, it seems, have been acquainted for a long time; and share a mutual fondness for a cappella choral singing. Together with Beck's dipsomaniac neighbor Malte (Philip Zandén), they form an impromptu trio: fueled by copious amounts of calvados, they embark on a rendition of "Danny Boy" (in English). This might be the only popular song they collectively know, but they perform it highly competently at least twice, the last time at the very end of the episode, as the camera moves slowly out of their apartment to focus on a Swedish sunset, the river glittering in the fading light.
Confronted by such unaccustomed matiness, Gunvald reacts in surly fashion to Hans, especially when acting as Hans's chauffeur, ferrying him to Ernst's mansion. It seems that the bond linking Beck with Gunvald has been severed; and Gunvald, for one, resents it. In response Gunvald becomes more and more aggressive in his police procedure; he gets results, but treats everyone with uncharacteristic disdain.
Although a self-contained episode, there are sufficient loose ends to keep us watching the next installment in the series - specifically what happens in Gunvald and Beck's daughter Inger's personal lives.