侦探督察迈克·谢泼德擅长自己的工作，却不善于建立关系，到“布罗肯伍德”市破案时决定留下来，但很快谢泼德开始与克里斯汀·西姆斯侦探发生冲突。
得知政府跟踪和控制儿童的阴谋后，孪生兄弟德鲁和卡尔与一群叛逃者联手夺回本属于他们的世界
歇洛克·福尔摩斯的药物成瘾的根源来自他的内心，在自己和华生医生的努力下，他暂时摆脱了毒品。可是，问题并没有消除，只是潜伏下来了，并且潜伏得很深。在第三季季终，福尔摩斯不幸复吸，其父听闻这一消息后赶往纽约。华生则在丧偶后回到福尔摩斯身边。
A year has passed, Lord Glendenning has died and Moray is working in Paris. Recently married to the philandering Tom Weston, who has a young daughter Flora, Katherine, now owner of the Paradise, summons Moray to return and revitalize the store, which is losing trade. On arrival back he proposes to Denise, who is still employed at the Paradise, and Audrey proposes to Edmund. New staff number shop-girl Susy and store-man Nathaniel, the former in love with the latter, unaware that he is a saboteur for Fenton, a rival tradesman seeking to buy the Paradise. Katherine is aware that Weston also wants the sale and urges Moray to make a success of the grand reopening. Suspicious of Nathaniel's actions, Denise exposes him, leading to his dismissal and a hugely profitable first day under Moray's management. Seeing its potential Weston calls off his deal with Fenton.
西西里检察官尼诺·斯科特拉罗 (Nino Scotellaro) 毕生致力于打击黑手党，却突然被指控为黑手党成员。被定罪后，尼诺变得一无所有，并决定实施权谋报复计划。
