 On the bridge, they find a drain engraved with Valley of Fear.Referring to "The Valley of Fear", they find a drain cover with the letter A in the river; "Now I remember to ask a cake to celebrate in advance" leads them to St Bride's Church where they find envelopes entitled A Scandal in Bohemia.Soaking the envelope in water reveals the letter S; "I'm a long nosed wizard in a castle" leads them to Elephant & Castle tube station where they find a man carrying a suitcase with the word identity on it.