It did not happen during one of escape, as Bess had feared. His death was caused by appendicitis. On Stage Houdini often invited people to punch him in the stomach, so they could feel his strong muscles. One evening after a show in Montreal, a student punched him before he was ready. This may have caused his appendix to burst (break open)
Houdini did not feel well the next day, but he did not cancel his show. Against the advice of doctors, He traveled to Detroit and event managed to do a show there. But then he collapsed. The burst appendix had caused a massive infection. In those day before antibiotics, there was nothing doctors could do at that point. He died on October 31, 1926---on Halloween.