'We are wandering in circles. We're clearly missing something...' Sherlock said, pulling on the violin strings restlessly.

'It's as if someone killed someone in a room without doors and windows, and then ran away.' Replied Amber lying with her feet up on the chair. 'Most would say it's impossible, but the question is...'

'...was there a roof.'

They fell silent and all that could be heard was the sound of Mrs. Hudson's vacuum cleaner downstairs.

Five suspects. None with a good motive. Poison in the victim's blood. What does it all mean...?

Suddenly Sherlock made a sudden movement, making Amber flinch.

'Have Lestrade call all the suspects here. Her husband, parents, brother and friend. They have to be here at seven o'clock.'

He walked over to the coat rack and quickly put on his coat and scarf.

'But...' She sat down normally in her chair and looked at him puzzled, wanting to keep up with his reasoning. 'Where are you going?'

'I have to check something.' Only said the detective and began to walk down the stairs to the exit, shouting. 'Remember, at seventeen!'

Amber rose from her seat and went to the window just in time to see Holmes catch a cab. Unfortunately, he was already practically in the vehicle when he told the cab driver where to go so she couldn't read the address from the movement of his lips.

***

Exactly at seven o'clock, there was a knock on the door at 221B Baker Street by Fabian Labkaster. Lestrade arrived as the last one, except Sherlock, when everyone was already seated in the living room, sipping tea given to them by Mrs. Hudson. 

Five after seven Sherlock entered the apartment with an energy almost unlike him. Immediately all eyes turned to him and all conversation quieted.

He exchanged glances with Amber and didn't bother to take off his coat, but began to walk in circles in the living room.

First, of course, he looked around at the assembled guests.

The corpulent, bald man who arrived here in a cab, as indicated by the fact that his hat was dry, is the victim's husband, Fabian Labkaster. The tall and dark-haired one with glasses is probably his brother, Tom. They have similar noses, the same as the elderly man sitting next to Tom with a cane in his hand and an elegantly trimmed beard - this is the father of the two, Greg Labkaster. He was holding his wife's hand. Juliet Bruce-Labkaster was a graying woman with gentle features and bright eyes. There is also a light blonde woman - Ann's friend, Maria Hope. 

All of the five suspects were in one place.

Sherlock cleared his throat, apparently trying to gather his thoughts of how to put into words the chaos of his mind.

'As you probably know-' He started loudly. 'We are gathered here to find out the identity of Ann Labkaster's killer, because - yes, it's true - she did not die because of a natural death. She was poisoned.'

Amber leaned against the door frame watching Holmes speaking. She, and everybody else in the room, were mesmerized by the view of the famous detective in action.

'Was it her loving husband?' Sherlock turned toward Fabian Labkaster. 'A jealous brother? Parents tired of taking care of her? Or perhaps a false friend?'

He fell silent, looking around at all the guests, watching their reaction as if he expected the killer to confess themself.

However, no one said anything, so Sherlock continued with his speech:

'However, the pieces of the puzzle don't fit together. If it was the husband then why didn't he arrange an alibi? If it was the brother then why would he kill Ann instead of her husband? If it was a false friend then what would be the point in doing so? Money? Revenge? And the parents? After all, they knew that their son loved her more than anyone else. So who? Who was it?'

He stood with his back to the guests and his front to the mirror, watching their reactions in the reflection. He was counting in his head, like a performer waiting for the crescendo to reach its highest value.

Amber twitched slightly. Is he suggesting that..?

'Are you suggesting that it's a murder without a murderer?' Lestrade, already knowing too well Sherlock's tactics, was impatient for the reveal.

The detective turned around, his right finger pointed to the ceiling.

'Yes. And no.'

The policeman looked at him as if he were crazy. (It wasn't the first time he had done that.)

'Sometimes you have flashes of genius.' Sherlock started circling the room again. 'But you don't see the obvious. The murder was committed in a locked room with no doors or windows. But-' He glanced at Amber. '-it had a roof. So how did the murderer get inside? And more importantly: how did they get out?'

Sherlock paused for a dramatic event, looking around.

'They didn't get in. Nor did they get out. It's very simple.'

He smiled as he saw the surprise and disbelief on the faces of the people gathered in the room, and smiled even wider when he saw the expression of understanding on Amber's face.

'Don't you understand? The murderer didn't get in, because they were already there! The victim was the murderer. Anna Labkaster committed suicide.'

'What?' Mrs. Labkaster jumped up from her seat, simultaneously with Fabian.

'Your wife and your son-in-law committed suicide.' Repeated the detective calmly.

'Are you sure?' Asked Lestrade, also surprised by this turn of events.

'I verified it. People usually leave letters. It was the same in this case, although the deceased didn't leave it directly with her and that's why the police didn't find it.'

He took out a small rolled-up roll from his coat's pocket and handed it to the still-surprised widower.

'I think this letter was meant for you.'

Fabian Labkaster was too preoccupied to read his wife's farewell letter at the moment and only held it in his clenched hand, while his mother tried to comfort him.

'Where did you find it?' Lestrade asked Sherlock when even Mary Hope rushed over to assist Ann's husband.

The detective smiled mysteriously.

'And where would you leave the letter if you wanted to commit suicide? She put it on her bedside table but did not anticipate that her husband, due to the pain of her loss, would not notice the presence of this inconspicuous piece of paper. Fortunately, I resolved the matter before there was a dangerous conflict between the brothers.'

Lestrade opened his mouth, wanting to say something, but frowned and closed it. He decided not to say anything and then left.

Amber approached Sherlock with her cheeks slightly flushed with emotion.

'You have solved the unsolvable mystery. Amazing.'

'That's what my job is all about.'

'But what if she was forced to write this letter by this killer?'

He looked at her strangely.

'She wrote it of her own free will.'

Amber raised one eyebrow.

'You read it.'

Sherlock turned away, suddenly showing much interest in Mrs. Hudson refilling everyone's tea.

'I couldn't. This is private correspondence.'

'You read it.' She repeated, now with a smile.

A small, almost unnoticeable smile appeared on his face and he winked at Amber. She shook her head in disbelief, but she couldn't help but smile too.