CREATE TABLE "series_2" (
  "episode" real,
  "title" text,
  "story" text,
  "adapted_by" text,
  "director" text,
  "airdate" text,
  "exists" text
);

Question: What is the airdate when the story is listed as hugh leonard?
SQL: SELECT "airdate" FROM "series_2" WHERE "story"='Hugh Leonard';