(lc)which sentence below shows correct use of em dashes?

by the end-of-the-story, no one could believe it the main-character, was dead.

by – the end of the story no one could believe it, the main – character was dead.

by the end of the story, no-one could believe it the main, character – was dead.

by the end of the story – no one could believe it – the main character was dead.