1989年的5月，一起溶尸奇案轰动香江。美丽的空中小姐Brenda（贺恩 饰）被人杀害，并投入强酸池中溶蚀分解。不久，其前男友汪德明（吴镇宇 饰）及其现任同居女友Kitty阮（梁思敏 饰）作为嫌疑犯被警方拘捕。

　　一年后，备受感情困扰的社工Shirley（叶童 饰）出入女子监狱对Kitty进行心理辅导。此时Kitty的情绪极不稳定，为了汪德明先后两次自杀。为了帮她重振生活的信心，Shirley来到赤柱监狱探访汪德明。几次见面后，汪开始向其袒露心迹以及和Kitty交往的经过，Shirley也向汪倾诉了自己的情事。拥有情感创伤的两人对彼此渐生依赖，而Shirley也开始为汪德明的清白奔走呼告……

Based on a true story. A female bible student corresponds with a couple that is sent to prison after a goopy body is found in their apartment in a trunk filled with acid. After visiting the Wife, then the husband, she (Cecilia Yip) falls for him (Francis Ng) and begins to think that he is innocent. So she arranges for a defense team (with help from a catholic Church) to get him acquitted of the charges. Meanwhile a hard working detective (Anthony Wong) tries to convince the woman that he's guilty as hell. But he arranges to have a prison divorce and wedding behind bars. When she finds out the awful truth, how will she handle it?

En mai 1989, Brenda a été assassinée, puis son corps fut dissous. Plus tard, Patrick, son ex-petit ami et Kitty, sa nouvelle fiancée, sont arrêtés et jugés coupables de meurtre.

Plus tard Patrick épousera depuis la prison, Shirley, une avocate qui fera tout pour le libérer.

Mais petit a petit, Shirley, découvre la vraie nature de Patrick.