This scene comes from Greek mythology. According to one version of the story, Orestes (son of Agamemnon, king of Mycenae) and his companion, Pylades, were sent on a mission to retrieve a sculpture of the goddess Artemis. They were captured, however, and brought to the temple to be sacrificed. Luckily, the temple's high priestess, Iphigenia, turns out to be Orestes's sister, who he believed was sacrificed long before. Overjoyed by their reunion, Iphigenia saves Orestes and Pylades and helps them obtain the statue.
Agostino Musi was born in Venice and was a pupil of Giulio Campagnola (about 1482–after 1514) before going to Rome, where he worked under Marcantonio until 1520.