‘Behind The Shadows’ review: Louis Koo plays a hardbitten PI in Kuala Lumpur-set detective thriller

Dirs: Jonathan Li, Chou Man-yu. Hong Kong/Malaysia. 2025. 103mins.

A shady private investigator (Louis Koo) agrees to find proof that a client’s girlfriend is an adulterer, only to be flummoxed by the discovery of his own wife’s philandering. A marriage drama dressed up as a detective thriller, Behind The Shadows never tips all the way into hard-boiled territory, but immerses itself deeply enough in genre convention to have fun with its central murder mystery. A few narrative curveballs and an effective exploitation of Kuala Lumpur’s dark corners and muggy spaces – palpably captured by cinematographer Tam Wai-kai – result in an engaging diversion.

Koo almost single-handedly makes the film work

In fairness, co-directors Jonathan Li and Chou Man-yu are not that interested in the murder mystery; we get an idea of who the killer is early on. Reteaming after 2023’s gritty Dust To Dust, similarly a crime thriller on the surface but a drama about an antagonistic bond underneath, Li and Chou are more concerned with the betrayals, miscommunication, secrets and lies that can inhabit relationships.

This is the first Malaysian production from Hong Kong actor-mogul Louis Koo’s One Cool Group, which has been an active supporter of young filmmakers (such as Lawrence Kan’s In Broad Daylight) and broadening industry horizons (as with Ng Yuen-fai’s science-fiction epic Warriors Of Future). The film, which rolls out across Hong Kong and Malaysia from June 13, has taken a modest $8.8m at the Chinese box office since opening there on May 31, but the presence of Koo, together with its pan-Asian cast, semi-anonymous location and acessible storytelling pitched to regional audiences, could see it perform strongly across southeast Asia. It should also do well on streaming platforms.

Au Yeung Wai-yip (Koo) is a Hong Kong PI living in Kuala Lumpur with his Malaysian wife Kuan Weng Sam (Chrissie Chau). The couple clearly have issues after several years of marriage – Au is feeling unfulfilled and Kuan wants to start a family. One particularly lucrative day at his smoke-filled agency, Au takes on three clients. The first is a young man whose fiancée has vanished – a woman who may or may not be the same one seen murdered in the film’s prologue. The second is Clowy (Raymond Wong), a mid-level gangster who has been charged with figuring out just how unfaithful his boss’s moll Betty (Renci Yeung) has been.

Last is an average businessman who wants information on his cheating girlfriend, a woman who turns out to be Au’s own wife, Kuan. The story kicks into an even higher gear when Au stumbles on a second murder, and finds himself in the crosshairs of homicide detective Chen Heong Men (Taiwanese actor Liu Kuan-ting).

Co-director Chou has cited the likes of Raymond Chandler as an influence and, indeed, Behind The Shadows starts to blossom into a wrong-man mystery before recentring its focus on the characters’ mindsets and motivations. Au and Kuan’s broken marriage is the pivot for the PI’s other clients, and Chen’s lingering guilt over a car accident that put his wife in a coma.

The threads come together eventually, if a little loosely and with some sketchy psychology, but Koo almost single-handedly makes the film work. In a turn against his standard, coolly detached type, Koo cycles Au through dismay, rage, sorrow and acceptance in just the right doses. Chau, who is still better known for her leng mo pseudo-modelling career than her legitimately compelling performances in Kearen Pang’s 29+1 or Emily Chow’s Madalena, is underused, and Liu’s haunted cop has been blessed with much less colour than Au. Rounding out the multi-market cast, and giving the film some welcome texture, are Chinese actor Cai Xiangyu, Malaysia’s Yumi Wong and Kwan Tak-fai, and Eddie Cheung, another Hong Kong veteran who plays Feeble, Au’s occasionally helpful rival PI.

Behind The Shadows ultimately does not have the courage of its genre convictions vis à vis Kuan’s actions – or inaction. It redeems the character morally, making the film an easier sell in APAC, but still manages an ambiguous closing shot that is perfect for a pulp detective yarn.