A cryptic message on Tintin's telegraph, which initially didn't mean much, becomes the reason for a trip to Shanghai. The successive dangers he faces alternate with equal interventions of protection from unknown Chinese who never looked favorably upon the presence of the Japanese in Shanghai. And amidst the madness-inducing poison and the diabolical Mitsuhirato, the opium trade, organized by an old acquaintance of Tintin, spreads. However, the unexpected help from the Chinese saves him from the fatal at the most critical moment.