Liu also played a frustrated, but superhumanly gifted wallflower in “Detective Chinatown.” He was more convincing in those movies, partly because he was part of a winning buddy duo, but also because he wasn’t trying to capital-A act while wearing hairpieces, whose synthetic hairs thin at an alarming rate as his character ages. As Jinzhen, Liu brings to mind Russell Crowe’s performance as the schizophrenic mathematician John Nash in “A Beautiful Mind.” That association gets harder and harder to shake as Jinzhen inevitably loses his grip on reality while trying to solve the Black Cipher, a nigh-impossible encryption key that was specifically designed to stump Jinzhen.

Liu’s mostly compelling as a leading man whenever he can suggest a lot about Jinzhen by speaking softly and deferring his gaze, as if Jinzhen expects to be reprimanded or inconvenienced at any time. He’s still often eclipsed by co-star John Cusack, whose broad and twitchy performance often distracts from his dialogue, as well as a series of campy dream sequences that ostensibly speak for Liu’s introverted protagonist.

Jinzhen keeps a dream journal to help him break complex ciphers since the Freud-friendly symbols that he encounters in his dreams also help him to think out of the proverbial box. These dreams frequently hint at tensions that never gets resolved beyond portentous signs and awkwardly rendered computer graphics. Eventually, Jinzhen’s dreams overtake his waking life, which sinks “Decoded” deeper into a familiar and generally watchable scenario about a solitary genius’s triumph over impossible-seeming odds. But for a while, “Decoded” diligently and very slowly follows the various steps that lead Jinzhen along his defining quest to solve the Black Cipher.

Jinzhen passively tumbles from one encounter to the next throughout this 2.5-hour long dud. He’s first discovered by a distant relative, university professor Xiaolili (Daniel Wu), who adopts and nurtures Jinzhen. Then Jinzhen comes to the attention of Professor Liesiwicz (Cusack), a manic, but philosophically-inclined computational mathematics professor who refuses to collaborate with the Kuomingtang. “I hate war,” Liseiwicz declares at the end of an awkwardly phrased and negligibly dramatized speech. He’s soon forced to work for the American National Security Agency, for whom he devises increasingly difficult encryption methods, including the Black Cipher.