Conversation so far:
What was the Mirror challenge for Harry Houdini?
In 1904, the London Daily Mirror newspaper challenged Harry Houdini to escape from special handcuffs that it claimed had taken Nathaniel Hart, a locksmith from Birmingham, five years to make.

Question: Who challenged Houdini?
Self-contained rewrite: Who challenged Harry Houdini to escape from special handcuffs in 1904?