Watch The Heat Is Back On: The Remaking of Miss Saigon for Free: How to Stream the Movie Online at 123Movies. . Last seen in the West End 15 years ago, Miss Saigon has become one of the most successful musicals in history, seen by 40 million people worldwide. From the process of casting 40 actors from 18 different countries, to the reinvention of the staging, including the famous helicopter scene, The Heat is Back On takes us on a journey through rehearsals right up to the star-studded opening night. Featuring interviews with legendary producer Cameron Mackintosh, authors Alain Boublil and Claude-Michel Schönberg and many of the award-winning cast and creative team.