When the physician is unable to help Demetrius, they send for St. Peter. Peter orders everybody else out of the room. None of the pagans even know who he is, but the next thing they know, Demetrius is healed, when a few minutes earlier he was at the brink of death.
The martyrdom of Marcellis and his wife- they manage to embarrass Caligula's entire court in the process.
Marcellis defeating the centurion in a swordfight.