The episode begins with a scene from five years ago, in which Amaryllis and her friends try to escape the clutches of the island chief on a boat. They are relentlessly pursued by Moz and Kirisame, the leader's loyal warriors. They are in possession of a mysterious weapon that can petrify people and turn Amaryllis' companions to stone.
However, Amaryllis, who is at the other end of the boat, is only lightly touched by the petrification ray. She deftly removes the part of her hair that is about to turn to stone, stops the process and escapes by jumping into the sea.
From this tale of Amaryllis, Senku deduces the petrification weapon and hypothesizes that it follows certain rules. Suggested properties of the Petrification Beam include a limited range, the need to throw it to activate it, and a chain reaction that can be broken if stopped quickly.
The narrative then focuses on Ibara, the island's minister, who wields great power as deputy commander. Meanwhile, Ginro, who was in the sea during the Petrification attack, narrowly escapes the beam thanks to an accurate arrow shot from Ukyo that breaks the weapon's trajectory. So Ginro lands just outside the attack area and survives.
As the episode reaches its climax, Ibara and his men explore the ship and come across various unknown inventions. When they hear a strange noise, Ginro, who has been hiding on board the ship, is in danger of being discovered. But Suika distracts Ibara and his men with a clever diversionary maneuver in the Green Room and saves Ginro from capture.