The Green Hornet speeds to the airport, hoping to arrive before the plane of Prince Rafil of Kahara. He arrives a few minutes after the plane lands and barely manages to stop an assassin from taking Rafil's life. The next day, D.A. Scanlon asks to be allowed to post police guards outside the Kaharan Consulate grounds to prevent another attempt. The prince readily agrees.
That night, at a reception to celebrate Rafil's impending nuptials to Janet Prescott, Janet is called away from greeting guests to take an urgent phone call. While taking the call, she is chloroformed and kidnapped. Minutes later, Britt Reid arrives and agrees to have a private drink with Rafil and Janet. After discovering Janet is missing, Rafil receives a phone call telling him to return to Kahara and abdicate his throne or Janet will be killed. On his way to the airport, the Green Hornet kidnaps Rafil and tells him he'll save Janet for $25 thousand. Rafil agrees out of love for Janet.
Scanlon is furious at Britt for kidnapping Rafil, but Britt deduces that since no one saw anything suspicious that Janet must still be at the embassy and that Rafil's top aides, Abu Bakr and Col. Sarajek are behind the kidnapping. Scanlon asks if he's sure, which he is because the Green Hornet called to ransom Prince Rafil back to them.
Later, the Green Hornet brings Rafil along to collect his ransom from Bakr and Sarajek. After collecting it, Sarajek instructs the guards to be sure that he is in his car when it leaves because he doesn't trust the Hornet. The guards check and see the Hornet in Black Beauty and allow it to leave. A few blocks away, Kato stops the car and Prince Rafil removes the Green Hornet disguise he had been wearing.
Meanwhile, the real Green Hornet sneaks into the consulate. Rafil tells him about a wine cellar. Subduing the guard causes the rest of the consulate staff to find him, but the Green Hornet is able to rescue Janet. Rafil and Kato return to the consulate to aid the Green Hornet and Kato prevents two thugs from removing the Hornet's mask. As the police draw near, Green Hornet tells Rafil to keep the $25 thousand as a wedding present.
At the wedding, Rafil thanks Britt for being his best man and wishes the Green Hornet could be there after all he had done to help him. Britt says he is there, in spirit.