Detective Conan: Strategy Above the Depths

Fifteen years ago, the cruise Yashiromaru sank in what looked like a tragic accident engineered for insurance fraud by the Yashiro group. The scheme aimed to cash in on the payout while the company tried to hide its culpability. During that period, the CEO's husband, a ship architect, suffered a heart attack and drove his car off a cliff, tying his fate to the wider conspiracy.

Today, the Yashiro group launches the Saint Aphrodite, a luxurious 100 million yen cruise. Conan and his friends are invited aboard through Serena, and the voyage promises glamour and excitement. However, the shadows of the past begin to loom as old crimes resurface.

On the second day, the CEO is found murdered in her cabin, turning the cruise into a high-stakes crime scene. The crew and detectives scramble to secure the vessel and begin questioning suspects. Conan and the others start their own investigation, following clues amid rising tension.

Shortly after the CEO's murder, the President of the Yashiro group disappears from the cruise and is presumed thrown overboard by the killer. The mystery deepens as passengers and crew search the sea for any sign of him.

At the welcome party, Richard publicly deduces that Akiyoshi, the sub-designer, is the murderer. Conan challenges the conclusion, hinting that the culprit's motives and connections are more complex than a simple misdirection. This disagreement foreshadows a deeper conspiracy at work.

Kusaka, a scriptwriter working with Akiyoshi on a script, reveals that the accident from 15 years ago was a deliberate sinking planned for insurance. He explains that his own father was murdered when he discovered the captain's role in drugging and leaving people to die.

Kusaka triggers bombs and escapes by sea, prompting the Detective Boys to pursue him. More bombs are ignited as alarms blare and passengers scramble to evacuate the ship.

During the evacuation, the Detective Boys organize a hide-and-seek game and create a 'gold medal' from sea-shells for Rachel. The ship sways, and Rachel returns to a hiding place in an enclosed area, causing her to faint.

It is revealed that Akiyoshi is the true mastermind, having killed all three victims and manipulated Kusaka into thinking he did them. She also admits that her father was the captain who died when the ship sank.

Richard deduces correctly this time and arrests Akiyoshi, driven by the need to prove her guilt rather than defend her innocence due to resemblance to his wife. The breakthrough closes the case and shifts focus to rescuing everyone.

As evacuation proceeds, Richard and Conan realize that Rachel is missing. They locate her under the deck with a fire axe and, with a helicopter arriving, escape from the ship.

In the post-credits scene, Conan explains how he knew Rachel's location thanks to a volleyball clue implying a hard wall. The Detective Kids present an improved 'gold medal' for Rachel and place it on her.