A pair of handcuffs thought to betray the secret to Harry Houdini's most famous escape are to go on sale at auction. The wrist restraints, believed to have been used in the famed escapologist's daring Chinese Water Torture trick, were purchased by a private collector in 2006. Close examination of the iron cuffs reveal they had been adjusted to open when heated and held at a certain angle, and it is suspected Houdini used the secret to help him wriggle from his chains while hanging upside down underwater. The handcuffs will go on sale at an auction in London next week (12Dec13). They are expected to fetch up to $4,500 (£3,000).