Leo, Frank, and Hazel explore Rome. Hazel eventually leads them to the Pantheon. Hazel senses a tunnel that will lead them to Nico. Leo scans the interior, considering its infrastructure and where a secret passage could be located and determines it is near a shrine. He locates Roman numerals etched into the base of a Roman column and uses them to unlock a narrow secret passage under the building. Hazel determines nothing alive is underground and goes down first to assess the situation.

While she is gone, Frank and Leo discuss Frank’s vulnerability to fire. Leo assures Frank that he would never do anything to hurt him, and the boys note that both lost their mothers to fire. Leo ponders how he might handle Frank’s problem. Three middle-aged American tourists lingering in the vicinity glare at Leo and begin moving toward them. The men are possessed by eidolons who want to kill Leo. He jumps into the underground passage with Frank, who has transformed into a snake to fit.

The passage closes behind them, cutting Leo and Frank off from their pursuers. Finding themselves in a sloping tunnel, they march forward until they run into Hazel, who is pondering how to unlock a door.