After Dexter bungles a safe-cracking operation, MI5 and MI6 make a wager. MI5 must break into MI6's offices, open a safe on a specified floor in a specified room, and bring the contents to MI6. Drummond realizes they must hire a professional for this job - after all, he won't be losing the bet to his friend at MI6 - so he arranges for the release of a thief from prison, and Peter gets to babysit this man of dubious fashion sense and even more dubious principles while the ""caper"" is afoot. But is the bet on the level or is Drummond being manipulated?
