A bus carrying a number of people including Emma Stroud has been blown up by a bomb planted in her luggage by her son, Gilbert. Robin, investigating the case, is convinced that Gilbert is guilty. As he uncovers vital evidence, he is knocked unconscious by the boy and imprisoned and threatened with a terrible death.

Rumor has it that a valuable cargo of tin was thrown overboard during a storm. Robin heads for the Orient to check out the report.

Robin investigates the possibility of foul play in a coffee plantation fire --and winds up as a murder suspect.