user: ### NOW ANSWER:
Question: Who wrote the episode called "Mercury Falling"?
Columns: ['Ep. No.', 'Title', 'Director', 'Written by', 'Original Air Date', 'Production No.']
Types: ['real', 'text', 'text', 'text', 'text', 'real']
Sample row: [1.0, '"Instrument of Destruction: Part 1"', 'David Lane', 'Phil Ford', '12February2005', 1.0]
SQL:

assistant: SELECT "Written by" FROM "Table" WHERE "Title" = '"Mercury Falling"';