The chapter begins when Crono appears in Truce Canyon. He last found himself standing in the Telepod at the Millennial Fair in 1000 A.D., then suddenly transported to 600 A.D. Coming out of the Canyon and into Truce, he talks to people and finally finds out where he is. Everyone talks about Magus and Queen Leene, but there's no sign of Marle.
Crono then travels through Guardia Forest to reach Guardia Castle where he finds Queen Leene. When Crono enters the Castle, some soldiers stop him. But a woman, appearing to be Queen Leene, says that he is a friend of hers. So, Crono is allowed to roam the Castle unattended. While heading up to the Queen's chambers to find out what's going on, she reveals herself to be Marle in disguise.
While Marle explains that she was mistaken for the Queen, she suddenly vanishes out of thin air. As Crono heads out of the Castle, Lucca shows up. Lucca tells Crono that Marle is actually Princess Nadia from 1000 A.D.. So if Marle has vanished, something must have happened to the Queen in the past. Together, Crono and Lucca set out to find and rescue the real Queen before any more damage is done to history.