The episode begins with Yor, the "Thorn Princess," being summoned to a garden where she receives a new assignment. She is tasked with protecting Olka Gretcher and her son, the last survivors of a powerful underworld family who have sought refuge in another country. Yor is to accompany them on a cruise ship and ensure their safety until they can rendezvous with a foreign vessel at sea.

Yor is worried about her job at the city hall and how to explain her absence to her family. Her supervisor assures her that a cover has been arranged, allowing her to carry out the mission as part of her duties as a civil servant.

Meanwhile, Yor’s brother Yuri asserts his independence and reassures Yor that he can take care of himself. Despite his claims, he reminds Yor that he will always be there for her, even if it means confronting Yor’s husband Loid, whom Yuri distrusts.

Anya, Yor’s adoptive daughter, wins raffle tickets for a luxury cruise—the same one on which Yor is assigned to work. Loid, Yor’s husband and a secret agent, takes advantage of this coincidence to turn the trip into a family outing, unaware of Yor’s mission.

Onboard the cruise ship, Yor meets her charge Olka, who is disguised in a wig to conceal her identity. Olka expresses her desire to enjoy a bit of freedom during the cruise before her life in confinement begins.

Loid, too, keeps an eye out for potential threats on the ship. He is determined to enjoy the vacation with Anya but remains vigilant of his surroundings.

Olka and Yor, posing as her friend, share a quiet moment on deck. Olka reflects on the life she is leaving behind and confides in Yor that she and her son are now safe.

As the episode progresses, tension rises with the presence of other passengers who may pose a threat.