Table: episode_details
Columns: no_in_series
no_in_season
title
directed_by
written_by
original_air_date
production_code

Question: What is the title of the episode with production code 406?
SQL: SELECT "title" FROM episode_details WHERE "production_code" = '406'

Question: Who write episode number 48 in the series?
SQL: SELECT "written_by" FROM episode_details WHERE "no_in_series" = '48'