Thirty years ago, Yip Siu-tin, a hardened criminal, was apprehended for an audacious armed robbery that shook the city. As justice prevailed, Siu-tin was sentenced to prison while his daughter, Cheung Sum-yuet, sought solace in anonymity and embarked on a new life under a different identity. In an unexpected twist of fate, Sum-yuet found love and companionship with Yen Ho-yin, the affluent owner of a prestigious yacht company. Meanwhile, Chong Chi-kiu, an innocent child left behind by one of Siu-tin's ill-fated accomplices, found refuge under the nurturing care of Tang Sing-him. Their bond grew strong as Sing-him became Chi-kiu's foster parent and guiding light in this chaotic world. However, destiny had other plans in store for all involved. A sudden and fateful encounter between Sum-yuet and Chi-kiu occurred due to a tragic traffic accident. Little did they know that this incident would unravel a web of secrets intertwined with Siu-tin's release from prison. Haunted by her past and tormented by her father's presence, Sum-yuet finds herself trapped in a nightmarish struggle she can no longer evade. Her marriage to Ho-yin begins to crumble under the weight of undisclosed issues. Sensing the impending chaos, Yeung Yan-hiu, a relentless police officer with unwavering determination, launches an investigation into the enigmatic ties that bind Siu-tin and Chi-kiu. As the unresolved grudges from three decades ago resurface with vengeance, everyone involved in the long-forgotten robbery is unwittingly drawn into this intricate tapestry of deceit and treachery. The doors to their hidden pasts swing wide open once again as they confront their shared demons. Prepare yourself for Cánh Cửa Bí Mật - a gripping tale of redemption, betrayal, and the relentless pursuit of justice. Step into a world where trust is shattered, loyalties are tested, and the truth lies just beyond the threshold of secrets.