sam emails his friend tracy to find out more about the four clues. the black rock was an old 19th century slaving ship that was mysteriously lost in the south indian ocean with 40 crew aboard. however, the ship was last seen leaving port in an easterly direction, when it should have been sailing to the west. but, more relevant to sam, there is a boat called the "christiane i" leaving jakarta for the sunda trench. sam decides that he needs to get on that boat.