Answer - Tell - Pray

It's fitting Harry Houdini died on Halloween. In 1926, after a student tested Houdini's abs of steel with repeated blows, Houdini wound up in the hospital with what looked like a ruptured appendix. Many believe Houdini had appendicitis before the student punched him in the gut, but was too stubborn to seek medical attention. 

Before his death, Houdini asked to be buried in a bronze casket along with letters written from his mother. He also left a secret code with his beloved wife, Bess, and said if she ever held a seance that he would make his presence known with the code, which was later revealed to be:

 Rosabelle- answer- tell- pray, answer- look- tell- answer, answer- tell.

The name Rosabelle came from a song that Bess sang when she and Houdini first met. The other words related to secret messages used between a magician and assistant during an act. Apparently each word corresponds to a letter, which ultimately spells out the word "believe". 

Every Halloween, Bess would try to contact her famous husband, but to no avail. Finally, after ten years, she threw in the towel, announcing: "My last hope is gone. I do not believe that Houdini can come back to me, or to anyone...The Houdini Shrine has burned for ten years. I now, reverently... turn out the light. It is finished. Good night, Harry!"

Even so, every Halloween there have been seances to try and contact the escape artist. As part of their "31 Days of Halloween", Atlas Obscura has some nice photos of Houdini's gravesite here.