Inspired by the sensational real-life tabloid fodder that jolted Hong Kong in 2006, "That Demon Within" centers on an unstable cop's psychological deterioration throughout the investigation of a grisly diamond heist.
Not unlike most of its Hollywood counterparts, though, this Hong Kong import can't resist the urge to dumb down a fascinating premise for the sake of mass consumption.
The screenplay, co-written by Jack Ng and director Dante Lam, alchemizes the irredeemable real-life dirty cop Tsui Po-ko into the tormented hero Dave Wong (Daniel Wu), who is resolved to apprehend the diamond thieves.
The heist sideshow often hijacks the main attraction that is Dave's impending meltdown, dissipating the plot. The film sets out to establish the parallel and duality à la "Infernal Affairs" (and its remake, "The Departed") between Dave and armed robber Hon Kong (Nick Cheung) — whose life Dave unwittingly saved via blood transfusion — but hardly any concrete link materializes.
Lam degrades the complex issue of mental illness into a mix of pedestrian psychobabble, overwrought expositions and hyperstylized hallucinations. Disinterested in the actual symptoms and effects of schizophrenia, the film ascribes any shopworn psychosis imaginable to Dave. Had Lam treated mental illness as a serious subject, "That Demon Within" could have been the next "Memento."
"That Demon Within"
MPAA rating: None
Running time: 1 hour, 52 minutes
Playing: At AMC Atlantic Times Square 14, Monterey Park; AMC Puente Hills 20, City of Industry; Laemmle's Playhouse 7, Pasadena.