Mr. Whittaker has been finding mysterious letters in the Imagination Station. One requested a Viking sunstone to save a man named Albert from being locked in a tower. The other asked for a monk’s silver chalice from Rome. Mr. Whittaker is currently unable to use the Imagination Station, so he asks two cousins, Patrick and Beth, for help.
Patrick and Beth notice that the sunstone they brought back is missing and ask Mr. Whittaker about it. He explains that he left it in the Imagination Station, and it simply disappeared. He assumes that the person who left the letters retrieved it. Mr. Whittaker explains that Albert is one of his ancestors. Mr. Whittaker visited Albert because he intends to write a family history, but now Albert is in trouble. Albert also gave Mr. Whittaker an ornate ring that can only be seen inside the Imagination Station.
Mr. Whittaker gives Patrick and Beth clothes to wear to Rome. Beth dresses in a slave’s tunic and Patrick wears a monk’s robe. Mr. Whittaker instructs Beth to take a bag of birdseed and gives Patrick a ruby armband, explaining that a man will ask Patrick for something valuable and that Patrick should give him the armband. Patrick and Beth climb into the Imagination Station. Once they arrive in Rome, they find themselves in a large arena.
The cousins hear a sound behind them and turn to see a tiger stalking them. The cousins begin to run. A slave tells them to hurry toward the gate in the wall. The slave guides them to safety. Beth and Patrick thank him, but he retorts that he only saved them because the tiger needs to be kept hungry for the games so that it will fight more viciously.
Patrick and Beth climb to the top floor of the arena, hoping that they can spot a church somewhere in the city. They see Roman soldiers returning from battle with men, women and children who were taken prisoner. Finally they see a church and decide to walk in that direction. Before they reach it, however, a soldier mistakes Beth for a runaway slave. He throws her over his shoulder and prepares to carry her away. Patrick wants to fight the soldier and save Beth, but a monk appears and cautions him against it — and says that if Patrick stays he will be made a slave, too.
Patrick and Telemachus, the monk, travel outside the city to a small cave where Telemachus is staying. Telemachus explains that he is not from Rome, but that God told him to come here. While Patrick and Telemachus are eating dinner, a large foreigner approaches them, demanding to share their supper. He explains that he was one of the Roman soldiers’ prisoners. He didn’t want to be forced to fight and die in the games, so he escaped.
The man threatens them with a knife and asks if they have any valuables that he can sell to assist in his escape. Telemachus gives him a silver chalice that was intended for use in the Lord’s Supper. Patrick realizes that this is probably the chalice he and Beth have been searching for. The man states that he is called Aldric and that one day he will repay them. Aldric flees into the woods, and soldiers soon pass through the camp pursuing him.
Meanwhile Beth has been carried to the emperor’s palace. Seeing the bag of birdseed, the soldier leaves her in the courtyard to tend the emperor’s birds. A young man approaches her, introducing himself as Honorius. Beth giggles at his name, not realizing that he is the emperor. A general approaches, and Honorius commands him to punish Beth. The general, however, is bringing a report on a military victory. The prisoners will be forced to fight to the death in the games the next day. Honorius pardons Beth but commands her to catch all of his beloved birds so that he can take them to the games with him.
The next morning Telemachus feels that God is calling him to the arena, so he and Patrick depart. As they arrive at the arena, a man approaches them selling tickets to the games. Telemachus explains that they have no money, but Patrick uses the armband to buy them seats near the emperor’s box. Patrick sees the emperor’s procession enter and notices Beth with the birds.
He runs over to speak to her, but the soldier who originally captured Beth recognizes him. Thinking that Patrick is trying to help Beth escape, the soldier throws him in the cage with the prisoners. Patrick finds Aldric there as well. Aldric tells Patrick to stay close to him and promises to try to protect him. Patrick is given a weapon and placed in the arena with the other prisoners. They are told they must fight to the death and that the last man standing will be honored as a hero.
Before the fight begins, Telemachus approaches the emperor’s box and asks Beth to give Honorius a message. The message asks Honorius how he can allow these games if he is truly a Christian and also condemns him for using a chalice that was intended to celebrate the Lord’s Supper to salute death. (Honorius now has the chalice that his soldiers took from Aldric when he was recaptured.) Honorius is troubled by these words and tells Telemachus to enter the box.
Honorius commands the prisoners in the arena to wait, but no one hears him, and they begin fighting. Aldric tries to defend Patrick, but there are too many opponents. A panicked Beth throws birdseed into the arena and all of the emperor’s birds flutter down into the battle, creating a distraction. Aldric takes the opportunity to throw Patrick up toward the edge of the arena. Patrick is able to grab hold of the net that surrounds the emperor’s box and climb to safety.
Honorius is finally able to stop the fighting, but the crowd is enraged by the interruption to the games and wants to stone Telemachus. The emperor returns the chalice to Telemachus, who sadly states that it is no longer fit to use in Communion and gives it to Patrick instead. The Imagination Station reappears, everything freezes and a tall knight steps out. He asks Patrick and Beth to tell Mr. Whittaker to search for the tablet of Kublai Khan next. The knight leaves with the chalice, and Patrick and Beth return to Whit’s End.
Mr. Whittaker explains that no one really knows what happened to Telemachus but that the games were never held again after that day. He tells Patrick and Beth to go home and rest — but asks them to return the next day to help him find the tablet.