Ralph Thomas enjoyed the book too so they decided to option the rights. These ended up costing four times more than Box originally thought after Hichcock had his own agent, as opposed to the publisher, do the negotiations. Box and Thomas paid for the rights themselves "not without a fair amount of heart-searching", Box wrote, "as we didn't expect it to be a straightforward financing operation – with the amount required to make a film it seldom is – but this was certainly not a subject I expected Rank, our traditional partners, to finance. They very soon turned it down without even reading it."