“I never make exceptions. An exception disproves the rule.”Ten years ago, Mary Morstan’s father went missing and every year after this incident, packages containing a precious pearl began to arrive. Sherlock and Watson’s help is needed to unravel the mystery behind those packages.The Sign Of The Four is Sir Arthur Conan Doyle’s second Sherlock Holmes novel, published in the magazine as a story before turning into a book.The adventure stretching from India to London draws attention to Sherlock’s human characteristics at the forefront. As he always does, Doyle takes the readers’ breath away in this novel.