There are two girls who live in London. Their parents are dead. They are the nieces of two very different people, but these girls think in the same way. One girl is related to John Watson and the other is niece to Sherlock Holmes. Both are being hunted by a certain psychopath for their intelligence. Each must choose which side is good or bad, because the world is not in black and white, but shades of grey. The two could bond or become worst enemies. And the fate of the whole world rests on their decision.