In Dr. Stone Season 3, Episode 11, the story continues with the mission of the Kingdom of Science to obtain platinum, which is essential for their scientific endeavors. The episode begins with a flashback in which Kohaku, one of the main characters, searches the forest for a treasure hidden by Senku's father, Byakuya. However, she discovers that the treasure is encased in concrete.

Back in the present, Senku devises a plan to help Kohaku find the treasure. He sends her materials to make plaster. Following his instructions, Kohaku mixes the materials in a specific way so that the plaster expands and breaks the concrete. This allows her to access the treasure without making a loud noise that could attract attention.

Kohaku finds what she initially thinks is sand but soon realizes is actually gold dust and platinum. She sends these materials back to Senku. In another flashback, it is revealed that Byakuya, Senku's father, died after collapsing in a river, having spent years collecting these rare materials for Senku's scientific research.

Meanwhile, Ibara in the heavily guarded enemy kingdom discovers that the treasure has been retrieved. He recognizes some of the materials as those he saw on the Perseus (Senku's ship) and suspects there is an intruder in the kingdom. Ibara is portrayed as a vigilant guardian who is highly observant.

At the same time, Senku begins constructing a machine that uses platinum to produce an unlimited supply of revival fluid, a crucial substance in the story.

The episode ends with a sense of closure for this phase of the story but leaves viewers anticipating the next challenges the characters will face, as it becomes clear that the Kingdom of Science's infiltration of the enemy kingdom has been noticed.