You can purchase "Houdini" on Amazon Music U.S. or Amazon Music UK or watch the video on YouTube. Check out more Dua/Houdini whatnot via the links below.
UPDATE: Billboard has a breakdown of where some of the past "Houdini" songs charted:
Walter Brennan spent a week at No. 100 on the Hot 100 in 1962 with “Houdini”; Kon Kan hit No. 33 on Dance Singles Sales in 1989 with “Harry Houdini”; and Foster the People’s “Houdini” hit No. 37 on Alternative Airplay in 2012.