The monotony of thick smogshrouded London is broken by a sudden visit from Holmes' brother Mycroft. He has come about some missing, secret submarine plans. Seven of the ten missing papers were found with Arthur Cadogan West's body, but the three "most essential" papers are still missing. West was a young clerk in a government office at Royal Arsenal, Woolwich, whose body was found next to the Underground tracks near the Aldgate tube station, his head crushed. He had little money with him (although there appears to have been no robbery), theatre tickets, and curiously, no Underground ticket.