The story begins with the monastery tunnelling beneath the surface. Bishop Celino is heading the expedition, with Master Gomez sounding out the rock, testing whether it is safe to drill through. Velasco, a young recruit, has volunteered to help with the expedition and has been there for three years. He is called to Celino's office and asked to tend to Marino, founder of the Magisterium, for the remainder of his expedition. Velasco, a quiet man who likes his solitude, dislikes the task but agrees. Later that week, Velasco is surprised when he receives a package from Ciro, as the two had been estranged since childhood. He explains that he read a paper Velasco had written and felt the need to ask for forgiveness. Velasco takes the rich gifts enclosed, though is apprehensive.

The next day, Bishop Celino brings Velasco into his office and asks him about his assignment to Marino, though he is aware that Velasco is not too fond of it. He explains to Velasco that the Divine Council has had a change of heart about the expedition, going so far as to question whether or not it would be harmful to make contact with the so-called demons. Velasco grows mad, but Bishop Celino explains that their decision may be swayed should they convince the guests of the Divine Council, including Marino, of the usefulness of the expedition. Velasco reluctantly agrees to the task, though he has doubts whether or not he is the right one for the job.

A short while later, Bishop Celino decides to start drilling again, dismissing the extensive sounding they normally do to impress the guests, and Velasco shows them the various equipment they use while drilling. The guests are impressed. However, because they did not properly sound out the rock beforehand, the drill shattered against it and hit Carlo, mortally wounding him. After the digging is suspended, Velasco goes to explore the catacombs himself. However, several strong quakes trap him behind a node gate (which locked to subdue the tremors) leading him to realise that they were digging through the volcano.

When Velasco returns, he finds the team performing a funeral ritual for Carlo, who had died since Velasco had left. The entire team is worried that Carlo's death means the end of the expedition to the subterranean realm and decided to finish as much as they could before the Divine Council shut down the project. However, it isn’t until almost two weeks later that a messenger (Tomás/Electra – parent of Angelica?) brings news to the team that they want the project finished in memory of Carlo and to build a shaft downwards to the subterranean realm to be built immediately. Soon, the team finds the perfect place to build the shaft and know their expedition is nearing its end. They soon find their expedition is taken over by the Divine Council and several members of the [newly-established] Magisterium.

The Divine Council brings in four dragons to finish the tunnel (which was unprecedented at the time as they had never employed all four together before) as the original team members grow anxious. However, after several weeks, Celino brings Velasco into his office and confesses that the Divine Council will not allow the team to visit the subterranean realm and will be sending them home. Velasco and Celino are heavily disappointed but accept it.

Several days later, Celino pulls Velasco aside again, this time to tell him that the Divine Council has reconsidered and are allowing Celino and six of his choosing to join them beneath the surface, with Velasco being one of the six.
(The six are: Velasco, Oceano, Ciro, Pietro, Louis Loral I and Hugo)
Velasco is ecstatic and thanks him, but he mentions that it was Ciro, sitting in for Lord Sancho on the Divine Council, made the suggestion and will be at the site in seven days to meet with Velasco in person.

Several days later, Ciro (along with Pietro) meet with Velasco. The two are very thankful to each other and Ciro asks Velasco to visit him in Italy. Velasco ponders this, wondering if Ciro truly has changed. Shortly after, Bishop Celino pulls Velasco aside and tells him that whether or not they step into the subterranean realm will be debated by the Divine Council. Velasco iis apprehensive and worries over the decision. Later that night, Velasco is awoken in the night by tremors, but is reassured by Master Gomez. They awake and watch the breaching ceremony (drilling to open the tunnel to the subterranean realm) and Ciro postpones their meeting to a later time. Velasco grows even more apprehensive about their friendship.

That night, another earthquake shakes the catacombs, sending Velasco crashing into the ceiling. Velasco rushes out of the craft and finds the walls of the catacombs collapsing. Bishop Celino finds him and tells him that Master Gomez has died, falling over the edge when the quake hit and instructs him to put on protective gear and sends him to the lower chamber. Velasco rushes down the ladder (his main way blocked by a sheet of marble) and finds Ciro trapped in a caravan, barely clinging to the cavern walls (which were damaged by the quake). He jumps down into the caravan, praying that it does not fall, and attempts to rescue the badly wounded Ciro. However, as they attempt to leave, another quake shakes the caravan free. The men, certain that death is upon them, scream, but are saved by a dragon, who catches them mid-fall. Immediately afterwards, the Divine Council orders the shaft repaired and sealed before meeting with the subterranean demons.

Two weeks later, Velasco meets with Ciro on an island somewhere off the coast of Italy and they discuss Velasco's brave act. Ciro makes a solemn pledge that should Velasco need anything within his power, Ciro will make it happen. Velasco comments that they should be friends without obligations. Ciro agrees, commenting on the hardship of owing one’s life to another.