To Catch the Uncatchable (棟篤神探) is a 25-episode TV sitcom produced by TVB of Hong Kong, which stars Dayo Wong as the genius (albeit physically weak and with asthma) CID Mok Tsok Tung (莫作棟) and Ada Choi as Vivi Lee Wai Wai (李慧慧), an insurance agent, with Marco Ngai and Michael Tong as major background characters.

The title of the series is of Cantonese word-play and innuendo (the title itself means "The Hilarious God Detective"), and the series itself sets itself apart from other TVB comedies before it thanks largely to the comedic stylings of Dayo Wong, plus new styles of acting and directing and camera work, different styles of plots unheard of before in comedies, and a surprisingly tragic conclusion.

The drama is centered around the exploits of Detective Mok (Wong) unmasking murderer that seemingly related somehow to either his "rival" Vivi (Choi). or getting critical inspiration from unorthodox sources, such as old television programs that his mother (whose face is not seen until later into the series) starred in, which Mok then translates in his investigative work...sometimes to the chagrin of Vivi, who often finds herself at the butt of Mok's investigations.

Thanks to these machinations, Vivi concludes that Mok is the source of her bad luck, which of course leads to her becoming suspected of a number of the murders. However, besides Mok, Vivi has a few thorns of her own: the despicable rival agent and lady-killer Romeo Lo Mat-au (羅密歐, derisively called 蘿蔔歐 lo bak au, which is a derogatory term for Japanese people) by Vivi (played by Marco Ngai), and a clueless smitten admirer in her personal trainer Jim (played by Michael Tong).

As the plot goes on, the couple found out they are, in fact, in love with each other. In later episodes, Mok was rendered unconscious by a murderer using a glass bottle which, coincidentally happened to Jim Jim. Reviving a month later because the blood clot moved, he proposed to Vivi right away. Later, his friend Dr. Yu (played by Hu Fung/胡楓) revealed to him that the blood clot in his brain is moving to a spot that will kill him instantly without any forewarning, unlike Jim Jim, whose clot moved to a safe spot, a bit of news that Mok decided to hide the fact as to keep everyone happy.

In the last episode, during taking a wedding photo with Vivi, Mok spotted a thief sneaking into another's bag and decided to rush out and chase the thief. After chasing the thief, Mok finally caught a thief for the "first" time in his career. After handing the criminal to his colleagues on duty, he told Vivi that he will be returning in 5 minutes on the phone.

In the original ending of the show, after he hung up, he falls down looking towards the sky seemingly happy. Scenes of memories and sorrow background music "Someplace Good" kicks in, with the show ending with the wedding photo of the couple turning black and white with Mok slowly fading away, leaving Vivi alone in the photo, which implies that Mok had died after falling down.

This ending received a large amount of feedback; in which one side praised it for its groundbreaking, unorthodox dour ending in a comedy drama, in contrast to TVB's usual endings (also known as the "happily-ever-after-plus" ending.) The other side criticized it for the unexpectedly dour ending in a comedy drama, which was too sharp of a contrast to the lightness of the series.

The latter opinion won out after they flooded newspapers, internet forums and newsgroups, and TVB claims that it is an original unedited ending, in which Mok still falls down but managed to get back to the photo shoot, albeit pensively. The alternate ending was shown on 27 August 2004 in local entertainment programme TVB Starbiz (娛樂大搜查), and was not included in any subsequent releases overseas.

The original reports of a sequel for To Catch the Uncatchable suggest that the 2005 Women On the Run (窈窕熟女) is the sequel, despite Women on the Run not being touted as such. Women on the Run has almost none of the original cast from TCTUC in it.