Even Prince Harry gets a bit jittery when Her Majesty pops up unexpectedly, or so he tells palace staff in this new trailer for HBO’s upcoming Queen of the World documentary.

“If you suddenly bump into her in the corridor,” Harry jovially advises the assembled staff, “don’t panic.” Then he chuckles and adds, “I know you will. We all do.”

Produced by Oxford Films for UK’s ITV network – HBO has U.S. rights – and exec produced by Nick Kent, Queen of the World includes behind-the-scenes footage with The Queen and such Royal Family members as Prince Charles and Camilla, Princess Anne, Prince William and Catherine, the Countess of Wessex and, of course, Prince Harry and Meghan, Duchess of Sussex and former countess of Suits. (Jokes like that are not recommended in the presence of Her Majesty, by the way…)

The new doc, filmed over the course of the year, chronicles Queen Elizabeth as a “figure on the global state” and “the baton she is passing to the younger members of the Royal Family…”

Queen of the World debuts Monday, Oct. 1 at 9 pm ET/PT on HBO.

Check out the clip above.