Heartwarming video from the Newsflare vault of a boy getting a surprise visit from his sister after nearly a year apart moments before he goes on stage for a high-school theatre show.

Hagen's sister Sadie had never seen him on stage before so cut her trip short and travelled all the way from New Zealand, via Switzerland, to see him perform.

The emotional reunion happened just moments before Hagen was to perform at the show's closing night.

Hagen explains: "My sister had gone to au pair in New Zealand. She had been gone for 11 months and was supposed to be home in a month. She would miss my high school theatre show, and she had never seen me perform on stage.

"So my mother and her planned for her to come home a month early and surprise me on the closing night of my show. She surprises me when my cast mates and I are warming up because our show started in 20 minutes."

The footage was filmed in Yorba Linda in Orange County, California.

My sister (Sadie) had gone to au pair in New Zealand. She had been gone for 11 months, and was supposed to be home in one month. She would miss my high school theatre show, and she had never seen me perform on stage. So my mother and her planned for her to come home a month early and surprise me on closing night of my show. She surprises me when my cast mates and I are warming up because our show started in 20 minutes.