The Initial Deception: When Lo boards the yacht, the terminally ill woman introduced to the guests as Anne Bullmer is actually Carrie (Gitte Witt), a hired imposter.
What Lo Actually Witnessed: The real Anne Bullmer was kept hidden in Cabin 10 prior to sailing. Late that night, Richard Bullmer murdered the real Anne and tossed her body overboard into the North Sea. When Lo entered Cabin 10 earlier, she saw Carrie; when Lo later heard the struggle and splash, it was the real Anne being murdered.
The Conspiracy: Richard devised the plan to kill Anne before she could change her will or transfer her billions entirely to her charitable foundation. Dr. Mehta (Art Malik) and Captain Addis (John MacMillan) were bribed to falsify logs and corroborate that "Anne" was still alive aboard the ship.
The Climax & Resolution: After Lo continues digging, Carrie knocks her unconscious and locks her in a maintenance compartment below deck to protect the scheme. However, Carrie, horrified by the violence and Richard's ruthlessness, confesses the entire plot to Lo. Working together, they orchestrate an escape, leading to the exposure and arrest of Richard, Dr. Mehta, and the complicit officers. Lo successfully publishes the investigative exposé, vindicating her perception and overcoming her trauma.