His explanations to Lestrade were very meagre. Finally all things were said.
"And you are absolutely certain about your decision, Mr Holmes?"
Holmes just nodded: "Yes, but", he looked up, "May I keep the pictures just for a while? One of your men should meet me tonight at >Cleopatra's Needle<, I'll hand over to pictures to Scotland Yard for good then."
Suddenly one of the Constables interrupted. 
It was this Mr Carson who we'd met at the bank a few hours ago.
"Inspector Lestrade, Sir, if you don't mind, I could meet Mr Holmes tonight. This place is just on my way home. And coming back to here with the pictures; that doesn't matter."
"Very well. You're keen on a promotion, aren't you?!", Lestrade quipped, "But anyway. What do you mean, Holmes? Is it OK, if you meet Constable Carson then?"
Holmes nodded: "Yes, that won't be a problem for me. Let's say 11 o'clock this evening? I know, that is very late, but after this defeat I need a bit time for myself. You understand?"
Lestrade and the young Constable nodded as Holmes said "See you later Mr Carson" as he went out the door.
I could have sworn that Holmes slipped a small piece of paper to Lestrade, before we left.

I think it was quarter past eleven as the telephone rang. It was Lestrade:
"Doctor Watson, you must come to Holmes' meeting place immediately. And don't forget your tools of the trade!"
I was a bit distracted about this call, yet I slipped into my coat, grabbed my medical bag and raced with the next best carriage in the direction of Charing Cross.
As I arrived it was hard for me understand what was going on in front of my eyes: The young Constable, who wanted to meet Holmes here, was led away in handcuffs by some of his colleagues.
Lestrade talked to Mrs Carter and a young man, to all appearances Jonathan Carter, Mrs Carters husband.
But I saw Holmes nowhere.
"Over here, Watson!"
Sherlock Holmes was sitting on the wet lawn, pressing his hand on his shoulder.
"Holmes!", I run to him as quick as possible, "Holmes, what happened? My god, you're bleeding!"
"Now you're not the only one with a bullet in the shoulder."
Holmes tried to grin, but the pain seems to be too much and he clenched his teeth again.
"Would you please tell me what you've done this time, Holmes?!"
"I certainly will do, Watson, once you've fixed me up." he answered, undressing himself.
His shoulder doesn't look that much injured. "So, what happened?"
"OK, here are the news: I arrived here a few minutes before 11 o'clock. Constable Carson was already waiting for me. Don't think I went here to give the pictures to him, in fact I went here to punish him as he deserves." "Holmes!", I interrupted confused, "Are you going to tell me, that Carson was behind the crimes?!"
"Yes, Watson, I'm coming to that. As I said Carson was already waiting for me, as I arrived:

"Ah! Mr Holmes. You finally arrived. May I have the pictures?"
"Why not. The cases are solved now, and I have no need for them any longer."
"Yes, yes, I know. You already said that."
"No, Mr Carson, I said I'll give the pictures, the main-evidences to Scotland Yard, so that the crimes would be easier to solve. But I think after all I've seen and heard the crimes ARE solved now. Give it up, Carson. I know you're guilty!"
I drew my pistol and Carson looked at me furiously.
"Very clever deduction, Mr Sherlock Holmes. Really clever. You're right. I was the one who killed Ms Rodland. Do you want to know why?!"
Then I made the worse mistake one could made in such a moment. I had heard a noise from the
bushes and I turned around. I was absent just for a few seconds, but it was too much time. Carson also drew a pistol and shot my shoulder. It hurt like hell, and I sank to the ground. Carson walked towards me with a stone-cold, sadistic smile on his face. He placed the barrel of his revolver right on my forehead. 
I was at his mercy.
"Good old Alice Rodland. I'm sure, Mr Holmes, you know, that Alice and I were up to get married. And you also know my motive, don't you? She'd already change her last will. All of Alice's money would have belong to
me if she dies. And then she suddenly died in a suicide, the poor girl. This Idiot of Inspector really believed the words of a young Constable."
"And that was you, Carson. You'd planned it all. Your job at the police, the murder, the findings of the investigation."
"Precisely! It would have been the perfect crime, but just a short time after I saw the drawings of a young artist at the >National Gallery<. This Mrs Carter got the evidences for my guilt, such things mustn't exist. First of all I tried to steal the drawings, but unfortunately the >National Gallery< is far to close to Scotland Yard. As the exhibition was suddenly closed then, I saw my chance to get the pictures. So I visited Mr Carter. First he thought he could blackmail me, but to my luck he mentioned that his wife was very ill at the moment. So it was his choice, either he blackmailed me and his wife wouldn't be in pain any longer or he did what I told him. Then he implored me to leave his wife alone, she wouldn't know how important the pictures are, and he would surely destroy the drawings. I agreed. Later I heard the Mrs Carter went blind. I visited her husband a second time and warned him again, that he better not try to cheat me. Then everything went alright for me.
Until a few weeks ago. We just caught two burglars and during the interrogation one of them said Something about some drawings which laid in one of the boxes. The drawings still existed. So I did what was the easiest thing: This Mr Carter should open the boxes for me. Unfortunately he didn't know the number of his wife's box,that took too much time.", Carson took the drawings away from me, then he continued, "But now I got what I wanted. And with just one more shot, Mr Holmes, nobody will ever know!"
He was about to do me in, as I fortunately got an idea.
"But you will never know, why I suddenly showed my interest to this case, Mr Carson. More than one year I got nothing to do with it, but suddenly.."
"SHUT UP!"
Carson was really hysterical, but also he certainly was curious.
"Mr Carson, the next time you want to threat someone, you better make sure, that your victim don't keep a dog. You know, the animals can be very clever, and sometimes one can teach them nearly everything, also to find a special persons house and lead this person to a special place."
"Don't tell me that that cur..."
"Yes, Carson. This very morning the dog sat in front of my house, and later it 'introduced' me to it's owner."
"I will remember your words, Holmes. But now, before you will be pushing up the daisies, one last question: How did figure out that it was me?"
"I have to confess, Carson, it wasn't easy for me. You' looked completely different then on the drawing. But you'd made two mistakes.
1. You'd called your colleagues from the bank, but you were unable to describe the 'burglars'. Funny, because you'd 'called' while the crime happened and you'd 'been knocked out by them'.
2. You know what? In my left pocket I got your identity disc. You'd lost it as you killed Mrs Rodland. You certainly was in a haste, because you know that Watson and I would arrive at the antique shop soon, so you didn't noticed the loss. Funny how life can be."
In this moment Carson was handcuffed.
"You're under arrest, Carson. I can't belief I'd trusted someone like you. Is everything alright, Mr Holmes?"
"My shoulder hurts atrociously."
"Hold on, Holmes. I'd already called Doctor Watson. He should arrive soon. I'll go and make sure Mr Carter and his wife are OK. You were right. He was in Carson's flat. Ah, look. That must be Doctor Watson."

"And then your carriage arrived."
"Just in time to see to your shoulder. The best thing to do would be to go to the hospital, so that we get the bullet removed."
"Excellent idea, old chum. But let me first say good-bye to Mr and Mrs Carter."
Holmes got up and talked a bit with Lestrade and the young couple before he finally said good-bye to them. "There is just one last thing, I still don't get, Holmes. How was Lestrade able to know about this?"
"Did you noticed the thing with the note, I'd slipped to Lestrade? I told him the facts, and asked him for a few things. Surely I told a lie as I said I would stop to investigate in this case any longer. And, the plan worked. Okay, the thing with the shoulder wasn't planned, but now I finally will have enough time to sleep late, even if dogs bark in front of my door."