I apologise in advance - I hadn't realised how many story threads were in this episode - hence it's very long!
Disclaimer: I own nothing, I make no profit, I just come here to play!

John on weekly shopping mission,

Fights with chip and pin machine,

Sherlock fights a robed assailant

Attack had not been unforeseen.

xXx

John admits to mission failure

Takes Sherlock's card, goes back once more,

On his return a bank to visit

Break in on the fortieth floor.

xXx

Strange spray painted yellow signs

On portrait and on office wall

Placed for a specific person

They cannot be seen by all

xXx

First they try Van Coon's apartment

The man himself has long been dead

Dimmock thinks it's suicide

Locked apartment – shot through head.

xXx

Brian Lukis next to die

Freelance journalist – worked far east

Sherlock smiles, informs John Watson

Connections to the first deceased

xXx

Off to get some expert knowledge

Raz, an artist in the know.

Police arrive, he cuts and runs

Leaves poor John facing an ASBO.

xXx

A shop to which both men delivered

Was found in colourful Chinatown,

Solved mystery too of painted message

Seeing ancient numeric written down.

xXx

A lead, a possible third victim,

The empty flat of Soo Lin Yao

A sneak attack, a paper flower,

A clue to where they'll find her now.

xXx

Enquiries made at the museum,

Once more find the yellow paint

Again they seek young Raz's wisdom

And John must exercise restraint.

xXx

They follow trail to railway sidings

Many symbols on a wall

By the time John fetches Sherlock

Black paint neatly covers all

xXx

John had taken pictures of the

Wall, so clues were well preserved

Then back to the museum where

Soo Lin was working, unobserved

xXx

She had hid for fear of 'Spider'

Once her brother she had said,

Chinese Tong had sent him forth

All too soon Soo Lin was dead

xXx

Books from first two victims' homes

Delivered then to Baker Street

Search all night, no further forward

Poor John's near dead upon his feet

xXx

First day in new job near disaster

John sleeps while the patients wait,

Agrees it's wrong, apologises,

Then invites Sarah on a date!

xXx

They were going to the cinema

Sherlock says they might perchance

Like to try the Chinese Circus,

He's purchased tickets in advance

xXx

That night all three at the Circus

Witness some amazing feats

Sherlock with some help from John

And Sarah beat the Tong elite.

xXx

Back at Baker Street John offers

To send out for takeaway

Sherlock throws his coat and scarf on

In the flat he cannot stay.

xXx

Realisation comes at last

The code book – London A to Z

Back at home John is in trouble

From a nasty blow to head.

xXx

He cracks the code, goes home in triumph

No John or Sarah – where are they?

Sees the paint and realises

They are at the Black Tramway

xXx

They believe that John is Sherlock,

Gun is held against his head

If he will not give up treasure

Doctor Sarah will be dead

xXx

Time is running out for Sarah

As the heavy ball descends

Sherlock nearly strangled as

He fights so hard to save his friends

xXx

Toppling his chair John kicks

The crossbow round to save his date,

The 'spider' killed by crossbow bolt,

The police arrive but it's too late

xXx

Next day they travel to the bank

To see Van Coon's young blond P A

Tell her that the hairpin's worth

Nine million – takes her breath away.

xXx

General Shan sat at her laptop

Red laser dot upon her head

Moriarty takes no chances

Pulls the trigger – shoots her dead.