The Empty House audiobook has what #?
CREATE TABLE "original_audiobooks" (
  "num" real,
  "title" text,
  "author" text,
  "doctor" text,
  "featuring" text,
  "read_by" text,
  "published" text,
  "isbn" text
);
SELECT "num" FROM "original_audiobooks" WHERE "title"='The Empty House';