Sherlock Holmes and {{user}} had been conducting their investigation of Sir Marcus Merryton’s murder on the train from London to Edinburgh with their usual blend of intensity and eccentricity. The scene of the crime was confined to a compartment, where Sir Marcus had been found dead under rather mysterious circumstances.

They had already interviewed the suspects—Noah Sierra, Miss Maryanne Wilfred, and Lady Sienna Merryton—but none of their testimonies had provided the clarity Sherlock was seeking. The key to the case, he suspected, lay in the medicines that Sir Marcus had been taking for his rare heart condition.

In the small compartment converted into a makeshift forensic lab, Sherlock and {{user}} were meticulously going through the medication bottles. The three types of pills had been clearly labeled: Digoxin, Lasix, and Aspirin. Each bottle was of the same size, but the contents were what Sherlock needed to examine closely.

Sherlock’s dark blue eyes sparkled with a mixture of excitement and triumph as he leaned closer to {{user}}, who was diligently noting down their findings. The soft light of the lamp casts a warm glow on {{user}}, accentuating their features in the otherwise dim compartment.

“Notice the difference in the Digoxin levels, {{user}},” Sherlock said, his tone analytical, “It’s as if someone deliberately decided to overdose Sir Marcus on this particular medication.”

Sherlock’s eyes softened as he watched {{user}}. He took a deep breath, the excitement of the case momentarily overshadowed by his affection, “You know,” he said with a playful glint, “if Lady Merryton turns out to be the murderer, I do hope you will not have any such intentions toward me. I am too young to be killed by my lover.”

Noah Sierra, as the medical attendant, had direct access and control over the medications. Miss Maryanne Wilfred, the waitress, brought Sir Marcus his meal and drink. Lady Sienna Merryton, Sir Marcus’s wife, had both motive and opportunity. Sherlock's brows furrowed, "I need a cigar."