INT. 221B BAKER STREET/ LIVING ROOM - NIGHT

All is quiet. Sherlock is on the sofa, in a simple plain brown dressing gown with his feet up, engaged with John's laptop. The phone rings. Sherlock sighs, annoyed. He waits. Looks around. The phone is all the way across the room. It keeps ringing. Sherlock keeps waiting.

SHERLOCK

(muttering to himself)

Oh, for God's sake John!

He looks at the phone, still ringing, angry.

SHERLOCK

Oh, give it a rest!

Sherlock opens up Skype on the laptop and enters the username "Ruggedly Handsome Lestrade". He pauses for a moment of thought. The phone stops ringing.

SHERLOCK

Ah. You've heeded to my advice. How wise.

Beat. It begins to ring again. Sherlock shakes his head in disapproval then returns his attention to the laptop. He types in a password "*****". He is logged in to Lestrade's skype account. He clicks on one of the names to the side - "John Watson". He clicks call. The ringing of the laptop joins with that of the phone.

Eventually the call is answered.

JOHN (v.o)

(on the other end of the line, sleepy, tired)

Lestrade? Hello?

SHERLOCK

No. Sherlock. Wake up. The phone's ringing. Dear God, John, pick it up.

JOHN (V.O)

Pick it up yourself. And grow up.

SHERLOCK

I refuse. Why would I grow up? That's like inviting boring into my life.

John walks out of his bedroom, really peeved off, still half asleep. He picks up the phone.

JOHN

Hello?

(beat)

Murder? Weird one?

Sherlock drops the laptop on the sofa and walks to John, snatching the phone off of him.

SHERLOCK

(into phone)

Text me the address. I'll be there as soon as possible.

Sherlock hangs up and looks at John.

SHERLOCK

John, get dressed. We're going out.

JOHN

You first.

SHERLOCK

I'm already dressed.

JOHN

You're not going out there in your night gown.

SHERLOCK

I am. I have no interest in fashion. This night gown is perfectly acceptable.

JOHN

But it's freezing outside.

SHERLOCK

No. 2 degrees above freezing, to be precise. Either way, how cold it is is irrelevant so long as it doesn't exceed the temperature at which it interferes with my brain.

EXT. PLAZA - NIGHT

Blue lights flash from police cars surrounding a fountain boxed off by yellow tape. The water in the fountain is murky brown.

Sherlock, still in his night gown and wearing slippers, arrives on the scene with John. They are greeted by Lestrade.

LESTRADE

Happy hour of the night. Put a smile on.

JOHN

It's 2 in the morning. I can barely walk. Smiling is too much effort.

SHERLOCK

Don't mind John. He's being grumpy. I can't imagine why.

John snarls at Sherlock.

SHERLOCK

So, where's the body?

LESTRADE

Oh, you'll like this. There isn't one.

SHERLOCK

So how do you know there's been a murder?

LESTRADE

A young couple were passing by this here fountain slash wishing pool. Nobody else was here, they thought they might as well nick a few pennies.

SHERLOCK

I don't waste my time with petty thieves. Especially not at a penny-stealing level. I take pennies from John's wallet all the time. It isn't a crime as far as I'm concerned.

LESTRADE

The young couple are in hospital. Their arms partially corroded.

JOHN

Jesus.

LESTRADE

Don't worry. They got the proper medical attention in just the right amount of time. Damage is mostly to the skin. Not too serious.

JOHN

So... the water in the fountain burned their hands?

LESTRADE

Health and safety'll make a huge fuss in the morning. Anyway, there's a reason I called you, Sherlock. The fountain. Deduce away.

Sherlock bends over the fountain. He looks carefully at the liquid inside, noting the colouration.

SHERLOCK

What appears to be some Iron chloride deposits.

Sherlock feels the very edge of the fountain.

SHERLOCK

Water droplets all around here. Can't be from the fountain, it wouldn't reach over here. Also some on the marble paving. Hydrogen gas.

LESTRADE

What about it?

SHERLOCK

Given off from the reaction the fountain. Combined with oxygen in the air and condensed into droplets over here.

JOHN

Hold on, what reaction in the fountain?

SHERLOCK

Iron Chloride deposits. Lestrade, you said the couple burned their hands, it must have been a strong acid. Taking a guess- the acid in the fountain is highly concentrated hydrochloric acid which has reacted with Iron to produce Iron Chloride and hydrogen gas.

LESTRADE

Iron?

SHERLOCK

From hemoglobin.

LESTRADE

Nemo goblin? What?

JOHN

Hemoglobin. An iron compound that makes up blood.

SHERLOCK

Thank you, John.

LESTRADE

Nice. Well done. Forensics took quite a bit longer than you to work it out.

SHERLOCK

Let me guess, Anderson? No, improbable. He'd still be working at it. After all, that is the effect of a lack of brain cells.

LESTRADE

So, we're looking for some remains. Anything that'll get us some more information.

JOHN

Well, I'm stumped.

SHERLOCK

As always, I'm not. We don't need remains.

LESTRADE

We don't?

SHERLOCK

Because there wasn't a body to begin with.

LESTRADE

Then this wasn't really a murder?

SHERLOCK

Exactly. Thank you for accidentally wasting my time.

Sherlock is about to leave.

LESTRADE

Wait! For the benefit of everyone else, explain. I'm not about to close a potential murder investigation because of an amateur.

SHERLOCK

I'm not an amateur.

LESTRADE

I know. But Donovan and Anderson and pretty much everyone at Scotland Yard think so. Prove them wrong.

SHERLOCK

There's not as much Iron in blood as everybody seems to think. Only 2.5 grams. The Iron Chloride deposits suggest the Iron present in the fountain relates to around about a pint of blood. Best guess is it was donated blood. Get your people to tell you whose it was and phone them. If they pick up, they're alive, no murder investigation. If they don't, call me.

JOHN

Right. So we can go back home now? I can get back to sleep?

Sherlock and John walk away.

JOHN

And if you're wrong-

SHERLOCK

(interrupting)

Don't be expecting a call, John. I'm hardly ever wrong.

INT. 221B BAKER STREET/ LIVING ROOM - morning

The phone rings. Sherlock is on hand this time and picks it up.

SHERLOCK

(immediately as he answers the phone)

I can't be wrong. You've made a mistake.

Beat.

SHERLOCK

(into phone)

Ah, so I'm right. Then why have you phoned me?

Another beat.

SHERLOCK

I see.

He hangs up as John walks in with a hot cup of tea in his hand.

JOHN

So you were wrong then?

SHERLOCK

No.

Sherlock takes the tea off of John and takes a sip.

JOHN

Oi!

SHERLOCK

Thank you.

JOHN

That was mine.

SHERLOCK

Terribly sorry but I had to. You'd have spat it all out otherwise.

JOHN

I would have?

SHERLOCK

Yes. Now sit down, John.

John lets himself fall onto the sofa.

SHERLOCK

They've found out whose blood it was.

JOHN

And? Whose was it?

SHERLOCK

Yours.

JOHN

Mine?

SHERLOCK

You gave blood a few weeks ago. That's where they must have gotten it from.

JOHN

How do you know I gave blood?

SHERLOCK

You were boring me with the details of your life one day and said "Hey, I gave some blood today."

JOHN

Oh. I never thought you cared to listen.

SHERLOCK

Listen, I did. Cared? Not a single bit.

JOHN

So why would my blood be in a fountain full of acid in the middle of London?

SHERLOCK

Well, you've had your bad days, John. Maybe you were drunk. Or maybe it was Sarah inflicting some form of revenge heavy with symbolism.

JOHN

She broke up with me.

SHERLOCK

She broke up with you because of you. That's enough to warrant revenge. And I agree with her.

JOHN

Sherlock, you've got to take this case.

SHERLOCK

Why would I purposefully bore myself?

JOHN

Because this is really personal stuff.

SHERLOCK

I disagree. It was most likely random. You're not being targeted John. Only valuable people get targeted.

JOHN

I'm not valuable?

sherlock

Oh, wake up, John! Just because some people care about you and just because mummy said you were her "special little boy" doesn't make you a big enough fish to be to be any kind of a target.

JOHN

(passively)

Could've been Moriarty. I'm valuable to him 'cause he can use me to get to you, right?

Sherlock pauses for thought, hints of a smile emerging on his face.

SHERLOCK

Phone Lestrade. Tell him I'll take the case.