Mrs Hudson didn't talk much of her early days. From people who knew her now she didn't talk much about anything that had happened to her before she went to Florida with her husband. She loved her husband, but she wanted something more. When Sherlock got him sentenced to death she wasn't upset - well, she was, but she wasn't as upset as she had been, in 1979, when she said goodbye to two people she loved but couldn't be with.

She hated today; of all the days in the year, she dreaded this one. But she did the one thing she allowed herself to do: open the box she kept hidden away. Inside this box was what she would call her most treasured items, but to anyone else they were just photos and letters. She picked up the first letter at the top of pile and smiled then she began to read.

Dear Martha,

I hope that you are well. I know that you probably get upset with me sending you these letters, but I knew the woman that I fell in love with would want to have a little bit of contact. I see that you send a Christmas card every year, so I guess that you still want me to keep writing. You know how to contact me if you want me to stop.

I just wanted to tell you that our little girl is growing up so fast. She just finished her first full term at primary school and she's loving it. She's so smart. When she smiles, she reminds me of you. She's top of her class - like I said, she's so smart, she'll probably become a scientist or doctor when she grows up. Talking of your Christmas cards, she always keeps them. When I asked her why, she said that they were alway her favourite because they have the prettiest pictures on them; if only she knew they were from you, I wonder how she'd feel.

The picture that I put in the letter is her first official school photo. She's so grown up. Nothing has changed with me - it's me and my little girl. I hope everything is okay with you. I'll write again soon.

With love always,

Your Henry xxxx

It made Mrs Hudson smile and cry reading this. She could hear his voice in her head, she could picture him all those year ago: the man she loved, the man she left, the man who never stopped loving then and she never stopped loving now. Next, she picked up more pictures.

One of a little girl on the beach, building a sandcastle, another of her sat in front of a Christmas tree, and one of the little girl and her dad stood in front of the Eiffel Tower. All of the photos had the same thing in common: the child in them always had a smile on her face. How she wished she could of been in those photos.

By the time she got to the bottom of the box, she could barely see what she was looking at through the tears in her eyes. She didn't realise Sherlock had entered her flat until he was stood next to her.

"If looking at that makes you cry, why are you doing it?" asked a very confused Sherlock.

"Oh, it's nothing, Sherlock. I'm fine, honest; it's just me being a bit silly."

Sherlock sat down opposite her and began to look at the stuff that was spread out on the table. He looked at everything and deduced what all this meant, but he knew he shouldn't be mean to his landlady. She was watching and decided it was time someone knew about her secret.

"It started in the late 1970s, before me and my husband moved to Florida. I was a bit wild in those days, and I met this man called Henry. He took my breath away the moment I saw him. I just couldn't stop thinking about him. It happened so quickly; it was beautiful. In a way, we fell in love. My husband barely noticed he was doing the same thing. If I didn't say anything he wouldn't say anything; he was unhealthy but it worked for us. Almost a year into my relationship with Henry, I realised I was pregnant. I knew it wasn't my husband's because he couldn't have kids, so I knew it was Henry's".

She stopped telling her story, just to make sure Sherlock was listening. He was looking at all the photos of the little girl. She looked strangely familiar to him. He looked up at Mrs Hudson, the expression on his face as if to say 'Why have you stopped telling the story?'

"I was scared, at first; I knew that I was having the child, but after it was born it was a different story, so I spoke to my husband first and explained everything. He told me that, as soon as it was born, I couldn't keep it. He had plans of moving us to America; he was setting up a business and wanted us to be moved within in the year. So I went and explained everything to Henry. He knew what we had wouldn't last forever, but we had try to hold on for as long as we could. He told me that he wanted this child no matter what, so that's what happened. I carried the child, and after she was born I only saw and held her once. I never even got to know her name; me and Henry had agreed that I wouldn't find out her name just to make it a bit easier. So after she was born, I moved to Florida, but Henry sent me photos and letters every now and then, just so I could know she was okay. It's her birthday today and I don't even know where she is, what life she lived. Is she married? Does she have kids? Am I a grandmother? Or worse, is she dead?"

Mrs Hudson started to cry again, so Sherlock gave her an awkward pat on the shoulder.

"Sherlock, can I give you a case? It won't be anything exciting, like you're used to, but it will be something that will mean a lot to me."

"You want me to track down your daughter, don't you?"

"Yes please, but Sherlock, if a more important case comes up, you can stop working on mine until it's done, okay? Oh, and Sherlock, please can you not tell anyone else about this case? Can we please keep it between ourselves?"

"Okay, Mrs Hudson."

After Sherlock had been given his case from Mrs Hudson, he decided to go to his favourite bolt hole - also known as Molly's flat. He texted just before going to make sure it was okay.

Would it be okay I went to your flat? - SH

Yeah as long as you don't mind me being here - MH x

No that's fine, be there in 10 minutes - SH

Sherlock let himself into Molly's flat with the key she had given him. He found her sitting on her sofa, watching some TV, with her cat Toby sat next to her. She looked up at him when he walked in.

"I guess it's your day off," Sherlock said to her, sitting down in his favourite spot next her on the sofa.

"Yeah, well, considering it's my birthday and everything, I thought I might take the day off and have some time to myself."

"Oh, sorry, I forgot it was your birthday...Why aren't you spending it with your family, rather than alone in your flat? I thought it would a good time for you to catch up with your mum or something."

"Sherlock, I, um...I don't mind spending it on my own. It gives me some time to just relax."

Still slightly confused, Sherlock asked Molly something he'd never asked her before. He had heard her talk about her dad before, but never her mother. How odd. "Molly, what is it your mother does?"

Molly took a deep breath. She hated this subject, but spoke anyway. "Look, I know you can deduce it, but I don't know her. I've never met her, so can we not talk about it? How about I order us a take away or something in celebration of my birthday? How about pizza, is that okay?"

He looked at her, nodded, and said, "That would be lovely, Molly, and I'll pay. Consider it a birthday treat."

She started to feel herself go red in the face, so she got up off the sofa. "I have a menu on the fridge. I'll go and order; do you want your usual?"

He nodded again.

As Molly left the room, something caught his eye: a photo. He got up and began to investigate. He picked the picture up. It was obviously a photo of Molly and her dad - Sherlock could have sworn he had seen the photo before.

Molly walked back into the room. "The phone was engaged, so I'm going to try again in a minute." She saw him looking at the photo. "That was me on my ninth birthday. Dad took me to Paris because I'd never been before and alway wanted to go. It was one of the best holidays of my life."

"You miss him."

"Yes, but not as much as I used to. I don't think he wanted me feeling sad all the time."

"No, Molly Hooper, he wouldn't."

They stared at each other for a moment.

"I'll try calling again; hopefully I can get through."

He nodded again and watched her walk out the room. He took one more look at the framed photo and smiled. Father and daughter in front of the Eiffel Tower...