Together, or Not at All (Superwholock)

There was something lurking on the campus of the university. It was evil, by far the most evil thing to be born in centuries. It had threatened several of the staff at Trinity College, causing them to leave the best jobs they had ever had. Only days later, all five of the threatened staff had died in mysterious circumstances.
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Was it an alien? The Doctor was intrigued by something new.
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Was it a demon? The Winchesters had travelled to England to find out.
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Was Scotland Yard out of their depth? Well, obviously. But Sherlock had a feeling the game was on.
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What will happen when three completely different sets of 'investigators' come after the most dangerous thing the planet had ever seen? It was worse than the Daleks, worse than Lucifer, worse than Moriarty. It needed to be stopped. But would the investigators' pride prevent them from setting their differences aside and defeating this enemy once and for all? Or would they band together as allies? In an investigation that will push all of them to their limits, it will have to be together or not at all.