Sherilyn Tan, a 40-year-old lawyer entangled in the quest for the Fist of Blue Sapphire—a legendary gem tied to a sunken pirate vessel off Singapore’s coast—acts as sponsor to karate champion Makoto Kyogoku in a tournament where the artifact is the prize. Her involvement entwines her in a broader conspiracy centered on the gem’s recovery and the criminal ambitions of Leon Lowe, a manipulative behavioral psychologist.

Her murder unfolds early in the narrative when her body is discovered at Marina Bay Sands shopping center, a stab wound to the back the fatal blow. A bloodstained Kaitō Kid calling card planted at the scene implicates the phantom thief, prompting Makoto’s withdrawal from the tournament after losing his sponsor. Sonoko Suzuki steps into Sherilyn’s role, reigniting the competition.

Investigations expose Leon Lowe as her killer, his plot to seize the sapphire and hijack an oil tanker targeting Singapore driving her death. To bury his schemes, Leon later eliminates accomplice Rachel Cheung. Sherilyn’s murder also intersects with Rishi Ramanathan’s vengeance against those linked to his father’s demise, her death fracturing both Leon’s and Rishi’s machinations.

Her professional history binds her to Singapore’s elite, including Zhon Han Chen, the millionaire who retrieved the sapphire, and Leon Lowe, whose pursuit of the gem masked darker ambitions.