19世紀末，俠盜馬奇劫富濟貧，令蘇格蘭場疲於奔命，但福爾摩斯卻在其私生女凱蒂的生日會上將他擒獲。

四年後，馬奇襲擊獄中老大刀疤熊，並攀越圍牆逃脫。福爾摩斯知其另有苦衷，只好讓他完成心願後才帶他自首。但刀疤熊突然出現，更劍指凱蒂。福爾摩斯和華生為救無辜，聯同孖寶幹探李大猩和狐格森出手營救。

一場生死大決戰在漫天花火中展開……深受歡迎的《大偵探福爾摩斯》圖書系列首度搬上大銀幕，知識與趣味並重，大人小朋友都不容錯過！

In the 19th century, the gentleman thief, Mack, was a difficult case for the Yard, but Sherlock Holmes managed to seize him at his daughter Katie's birthday party.

Four years later, Mack fights with the notorious Scarface in prison, and then climbs over the wall to escape. Sherlock understands that he has his own reason and decides to let him surrender afterwards. But Scarface suddenly appears and kidnaps Katie. Sherlock and Watson team up with detective Gordon Gorilla Riller and Carlson Fox for the rescue.

A battle between life and death is unfolding! The popular children's book series is adapted into animation for the first time! Don't miss it to be the first one to watch in cinema!