Also on tumblr (I'm on there under Fibrochemist), here is the alternate coffin scene no one asked for.
The next room was a windowless void, with a screen on one wall, the other three bare, save for the cameras. As Sherlock, John, and Mycroft entered, their attention was caught by a large stone object in the centre of the room, before Eurus' face came onto the screen and the next test began.
"Problem: someone is about to die, it will be, as I understand it a tragedy. So many days unlived, so many words unsaid, etc, etc, etc. Who, though, Sherlock? Please start your deductions, I will apply some context in a moment." She said in her unhinged manner, watching them intently.
Sherlock fought to keep his mask of cool indifference on his face, he had a gut-feeling where this would lead, and he hoped beyond hope that he was wrong.
"A sarcophagus. Size and carvings would imply it is intended for a female. Limestone, decorated with garlands, fruit, animals, symbols of love, fidelity-"
"Who loves you Sherlock?" Mycroft cut in, "Seeing as this is all about you,"
"Irene Adler," John jumped in, but Sherlock shook his head.
"Look again, John. Eternal love, guiding love, deep symbolic love, infinite capacity for love, practicality, brilliance, sincerity. Symbols for death, healing." His voice got softer as he pointed to each symbol in turn, "Molly Hooper," He whispered, leaning on the table, eyes shut as he braced himself,
"The length, Sherlock," Mycroft prompted, "It's longer than one would expect for someone of her height,"
"There's a third casket." Sherlock finished,
"She's quite alright for the moment, see, sleeping." Eurus interrupted, the screen switching to a grainy image, just recognisable as Molly. "That is, until she wakes up. Three minutes until she runs out of air Sherlock." A timer popped up on the screen, alongside the grainy image, and the infernal tick tock of Moriarty.
Sherlock narrowed his eyes in displeasure, and began inspecting the stone more carefully, it appeared that the outer stone had been sealed – three minutes, for the air to run out, for her to suffocate in a blind, deaf panic while he watched on, helpless. There was no way to lift the stone, nor to smash it or dissolve it. He ran his hand over the lid, feeling the grooves of the carvings, pondering what he would do in Eurus position when he felt something strange, a crack in the stone. He continued caressing the stone, until a pattern revealed itself – the carvings were an intricate puzzle. A twist to the left of the apple blossom, a half turn of the dove, the removal and replacement of Aphrodite, lead to a quiet click, and a sharp intake of breath that did not belong to Sherlock, John or Mycroft. The brothers shared a brief look, before the elder moved another two pieces, activating an internal mechanism that opened a panel in the lid, where the face and shoulders of the body may be, revealing, as expected, another casket.
The middle casket was made of lead, with a crowbar chained to the half not obscured by the unmoved portion of the outer casing. Sherlock looked up at the screen, 90 seconds was left on the clock, and Molly was starting to wake up. He forced himself to ignore her strangled gasp, and initial panic, instead focussing on the next puzzle that they had been presented with: a series of riddles, keys and padlocks. It was a full team effort, with Sherlock solving, John opening (Sherlock was shaking too hard to handle the keys), and Mycroft acting as a sounding board, and steadying his little brother as best he could. Five padlocks unlocked, the chains fell down, leaving the crowbar ready to free the final problem.
By this point, there was only thirty seconds left, and Molly was getting more vocal. She was flitting between baying for blood, and sheer, abject terror, unsure as to whether this was an experiment Sherlock had foisted upon her, or whether she was in true danger. Truth be told, Sherlock would rather she was screaming, even if it was for his own murder, at least it meant she was breathing.
The final coffin was revealed to be made of wood, a light oak, the top end of a lower price bracket, a practical, considered choice for someone without family, who would have to plan their own funeral. Everything Molly would have chosen for herself – except the plaque. Sherlock's nostrils flared, and for a moment the time stopped. I love you. Eurus cleared her throat, bringing him crashing back to reality.
"The release code. No warnings. You have thirty seconds,"
He knocked on the lid, and lowered his face towards the wood,
"Molly, can you hear me?" He half-shouted, watching the screen from his hunched over position. He saw her do a double take,
"Sherlock! Is this your doing?" She shouted back, unaware of the microphone by her ear.
"No! I need you to do something for me, I need you to say something," He replied quickly, all too aware of the seconds ticking down
"What?"
"Say these three words… I. Love. You." Sherlock said, as detached as he could muster.
"Is this some kind of a joke?!" Molly exclaimed,
"Please, Molly," He tried to keep his voice as level as possible
"You say it, you say it first," She demanded, coughing, the air was getting thin.
"I… I love you. I love you."
He watched her reaction, her face savouring a moment she didn't quite believe, or trust, before bracing herself to say those three little words. The clock kept ticking. 5..4..3..2...
"I love you," She whispered, reverently, into the ether. A bright light suddenly appeared, and she screwed her eyes tight shut.
The lid of the coffin moved slightly, as the electromagnets sealing her in were switched off, and Sherlock seized the moment to throw the coffin lid across the room, scoop her out of the confined space, and cradle her against his chest, burying his face in her hair.
Molly opened her eyes slowly, as they adjusted to the light, and she found herself in a windowless room, being held by Sherlock Holmes, while his brother, and John tried desperately not to watch. The shock of the last three minutes finally wearing off, she noticed his breathing was laboured, his hands shaking, and the top of her head was slightly wet.
A loud bang resonated throughout the small room, and two of the armed guards swooped in, ripped Molly from his grasp and marched off, before anyone could so much as blink. As she was dragged from the room he noticed she had been dressed all in white - all those days unlived, all those words unsaid.