The fourth series begins with the nation’s favourite detective, the mercurial Sherlock Holmes, back once more on British soil, as Doctor Watson and his wife, Mary, prepare for their biggest ever challenge - becoming parents for the first time.

A Royal scandal, a dazzling game of cat and mouse. The seductive Irene Adler is cold, calculating, brilliant. Has Sherlock finally met his match?

《神探夏洛克》是一部由BBC出品的英国迷你电视剧，该剧将原著的故事背景从19世纪大英帝国国势鼎盛的时期搬到了21世纪繁华热闹的大都市中。 试播集为原型短剧，从未在电视上播出过，2010年8月28日作为DVD花絮放出。 这一次夏洛克·福尔摩斯(本尼迪克特·康伯巴奇 Benedict Cumberbatch 饰)不仅是著名大侦探更是一名时尚潮人。这一集的故事从他与日后的好友兼得力助手约翰·华生（马丁·弗瑞曼 Martin Freeman 饰）如何相识说起。起初两人合租贝克街221B公寓时候，华生并不能忍受这个奇怪的室友。但在共同经历了离奇市民自杀案件后两人的关系明显改善。而华生原本左肩在战斗时中弹，留下了心理障碍导致的跛足，也在跟随夏洛克追踪凶手，穿越伦敦市区的过程中克服了心理上的伤残障碍而痊愈。 之后还有多少精彩绝伦的故事，只有让BBC的正式剧集来告诉大家了。

When a chance encounter brings soldier John Watson into Sherlock's life, it's apparent the two men couldn't be more different, but Sherlock's intellect coupled with John's pragmatism soon forges an unbreakable alliance as they investigate a series of baffling cases together.