Rome, 303AD: a time of great persecution of Christians. At a party at the palace, a troupe of painted, almost naked men, sporting huge phalluses, dance for the Emperor Diocletian.

When Sebastiane, the favoured Captain of the Palace Guard, speaks out against the killing of a young man, he is stripped of his rank and exiled to a remote island where the remaining action takes place.

As a Christian, Sebastiane is ostracised by the other soldiers and desired by the centurion, Severus. Despite being flogged, staked to the ground and humiliated, Sebastiane refuses to fight, clean his sword, or give in to the sexual advances of his captor.

He recites poems praising the beauty of God to the glistening sea, a seashell and the sun. Meanwhile, the other banished soldiers enjoy wrestling, bathing, beetle-baiting and throwing a golden frisbee under an intense Mediterranean sun. Only Justin cares for Sebastiane and tries to protect him. Two naked soldiers frolic and caress in a pool of water, while the centurion gazes longingly at Sebastiane. The centurion gets drunk and tries once again to seduce Sebastiane whose love of God makes him impervious to the lust of a mere mortal. He laughs in Severus' face. Sebastiane is shot with bows and arrows. Each soldier kneels on the ground before him as he dies beneath the wide blue sky and relentless sun.