The bank cellar ambush and Holmes's explanation

1 From three storeys up, a lamp-lit City street at night, where four tiny silhouettes file into the dark passage beside the shuttered bank.

2 Four small figures stand in the beam of a single lantern at the threshold of the bank's vast cellar.

3 In the pitch-black bank vault, a single lurid yellow spark flares in a flagstone joint, the first sign that the tunnel below is opening.

4 A white, almost womanly hand pushes up through a gash between the vault's flagstones, groping in a small pool of lurid yellow lantern light.

5 In the black bank vault, John Clay's lantern-lit face rises over the edge of the tipped flagstone and scans the dark.

6 In the lantern-lit bank vault, Sherlock Holmes bursts from the dark, seizes John Clay by the collar and raises his hunting crop over the gun hand.

7 In the lantern-lit bank vault, the cuffed John Clay bows low to Holmes, Watson and Merryweather like a prince leaving court.

8 A close, evidence-like study of the shop assistant's earth-stained, threadbare trouser knees, the clue that told Holmes of months of burrowing.

9 At dawn in the Baker Street sitting room, the weary detective shrugs off his friend's praise while the doctor listens with a fond smile over their whisky and soda.