Hassan Salah is a high-ranking official at the embassy in Los Angeles of the fictitious Middle Eastern nation of Suari (although both the name and the flag bear an uncanny resemblance to those of Syria). Hassan disapproves of the liberal ideas of the new young King of Suari, and devises a plan to disrupt his rule.
During a visit of the king to the embassy, there is a student demonstration against the old authoritarian regime in Suari outside the embassy's gates. Hassan tricks a code clerk, Rachman Habib, into supporting his cause and the two of them stage a robbery and murder the embassy's security chief, attempting to make the crimes look like the work of some of the more extreme demonstrators outside the embassy. The next day, Hassan betrays Habib by murdering him as well.
Columbo soon uncovers evidence that the crimes were an inside job in the embassy and of course suspects Hassan. However, he faces a seemingly insurmountable obstacle, in that Hassan has diplomatic immunity, and Hassan makes Columbo's life even more uncomfortable when he lodges an official complaint against him, which could get him fired from the police force.