CREATE TABLE table_27982 ("No. in series" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" TEXT, "U.S. viewers  ( million ) " TEXT)

Who directed episode number 18 in the series?
SELECT "Directed by" FROM table_27982 WHERE "No. in series" = '18'
SELECT "Directed by" FROM "table_27982" WHERE "No. in series" = '18'