Where Eagles Dare
The producer consulted MacLean and requested an adventure film filled with mystery, suspense, and action. Most of MacLean's novels had been made into films or were being filmed. Kastner persuaded MacLean to write a new story; six weeks later, he delivered the script, at that time entitled "Castle of Eagles". Kastner hated the title, and chose "Where Eagles Dare" instead. The title is from Act I, Scene III in William Shakespeare's "Richard III": "The world is grown so bad, that wrens make prey where eagles dare not perch". Like virtually all of MacLean's works, "Where Eagles Dare" features his trademark "secret traitor", who must be unmasked by the end.