Actually, Sherlock was given a case from India to solve. And when Sherlock landed in india, he came to know that the case is about Indrani Mukerjea.
And due to Sherlock`s overconfidence he accepted the case, but 15 days into the case, Sherlock got so confused that he couldnt figure out the actual family tree of Indrani and thus due to this defeat, sherlock, just couldnt take it and finally he jumped off the building. Actually, while figuring out the family tree of Indrani, Sherlock found that the Gladstone (Sherlock`s experimented dog) might come out to be her inter-species boyfriend. Due to Indrani`s kutte kaam, gladstone, got to know Indrani. And due to utter confusion, Sherlock gave away his life, may be now, Byomkesh Bakshi would be consulted for the case, if he is not another husband of Indrani.