CREATE TABLE table_29684 ("No. in series" FLOAT, "No. in season" FLOAT, "Title" CLOB, "Directed by" CLOB, "Written by" CLOB, "U.S. viewers  ( millions ) " CLOB, "Original U.S. air date" CLOB, "Prod. code" CLOB)

what is the number of the episode in the series whose production code is 405?
SELECT "No. in series" FROM table_29684 WHERE "Prod. code" = '405'
SELECT "No. in series" FROM "table_29684" WHERE "Prod. code" = '405'