You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.

Category: LITERATURE 
Clue: The first sequel to this classic French novel was titled "Twenty Years After"
the three musketeers

Category: EXPLORERS 
Clue: John Speke died just before he was to debate this former exploring partner on the source of the Nile
sir richard burton

Category: BOOKS & AUTHORS 
Clue: In the title of Sue Grafton's latest murder mystery "M Is For" this

malice