"Tantei Opera Milky Holmes Summer Special" is a short anime series that serves as a spin-off of the main "Tantei Opera Milky Holmes" franchise. The story revolves around the four members of the Milky Holmes detective agency: Sherlock Sherringford, Nero Yuzurizaki, Elly Cunningham, and Cordelia Glauca. These young detectives, known for their unique abilities called "Toys," which grant them special powers, find themselves in a lighthearted and comedic summer adventure.

The plot centers on the group as they embark on a summer vacation at a beach resort. However, their plans for relaxation are quickly disrupted when they encounter a series of mysterious incidents. The detectives must use their wits and teamwork to solve these puzzles, all while navigating the humorous and often absurd situations that arise. The narrative maintains a playful tone, with a focus on the quirky interactions between the characters and their exaggerated personalities.

Sherlock, the self-proclaimed leader, is determined yet often overconfident, while Nero is more laid-back and food-obsessed. Elly, the most serious and logical of the group, often finds herself exasperated by her teammates' antics, and Cordelia, the youngest, adds a touch of innocence and enthusiasm to the group dynamic. The series also features recurring characters from the main franchise, including rival detectives and antagonists, who contribute to the chaos and humor.

The episodic structure of the "Summer Special" allows for a variety of comedic scenarios, ranging from solving trivial mysteries to engaging in slapstick humor. The series emphasizes the camaraderie and growth of the Milky Holmes team, highlighting their ability to overcome challenges together despite their flaws. While the stakes are generally low, the focus remains on the characters' interactions and the lighthearted tone that defines the franchise. The "Summer Special" serves as a fun, self-contained addition to the "Tantei Opera Milky Holmes" universe, offering fans a chance to see their favorite characters in a new setting.