"Tantei Kageki Milky Holmes TD" is a spin-off of the "Tantei Opera Milky Holmes" series, focusing on the eccentric and comedic adventures of the Milky Holmes detective team. The story is set in a world where individuals possess supernatural abilities known as "Toys," which grant them unique powers. The Milky Holmes team, consisting of four girls—Sherlock Sherringford, Nero Yuzurizaki, Elly Himeyuri, and Cordelia Glauca—are former top detectives who have lost their Toys and are now struggling to regain their former glory.

The narrative begins with the Milky Holmes team attempting to rebuild their reputation as detectives after their fall from grace. Their journey is marked by a series of bizarre and humorous cases, often involving their rivals, the Gentlemen Thieves, who also possess Toys. The Gentlemen Thieves, led by Arsène, frequently challenge the Milky Holmes team, creating a dynamic of rivalry and competition. Despite their lack of Toys, the Milky Holmes girls rely on their wits, teamwork, and determination to solve mysteries and confront their adversaries.

Throughout the series, the characters face various challenges that test their resolve and friendship. Sherlock, the self-proclaimed leader, is impulsive and often overconfident, while Nero is more level-headed and analytical. Elly, the youngest member, brings a sense of innocence and optimism, and Cordelia, the most mature, provides a grounding presence. Their interactions and growth as a team are central to the story, as they navigate both comedic and heartfelt moments.

The plot is episodic, with each episode presenting a new case or challenge for the Milky Holmes team. These cases range from solving petty crimes to uncovering larger conspiracies, often with a comedic twist. The series balances humor with moments of character development, exploring the girls' relationships and their determination to prove themselves as capable detectives despite their setbacks.

"Tantei Kageki Milky Holmes TD" maintains a lighthearted tone, emphasizing the absurdity of its situations and the quirky personalities of its characters. The series also incorporates elements of parody, poking fun at detective tropes and the conventions of the mystery genre. While the overarching narrative is not heavily serialized, the episodic structure allows for a variety of comedic and adventurous scenarios, keeping the story engaging and entertaining.