what's the plot?

The Hound of Baskervilles. (Sherlock Holmes: A Game of Shadows. Robert Downey Jr., Jude Law.) It's a movie.

"They say that the best weapons are the ones you never have to fire. I respectfully disagree. I prefer you only fire it once. That's how Dad did it, that's how America does it, and it's worked out pretty well so far. Fire one of these off the chain and I guarantee you the bad guys won't wanna come out of their caves. Ladies and gentlemen: The Jerucho.