Tiger by the Tail

... with that old chestnut being a fake kidnapping that turns into a real one.

Lounge singer Bobby George (Sal Mineo) gets two of his acquaintances to fake his kidnapping, hoping to drum up publicity and thus popularity for his act. He has been estranged from his dad for years, so he is surprised when his wealthy father D. J. Gorgiade (Harold J. Stone) shows up and, unprompted gives a televised address saying that he'll pay anything to get his son back.

The two associates decide to hold George for ransom for real and extort 500 thousand dollars from his father. That would be about five million in 2023 dollars. But one is getting cold feet about the whole thing, especially when the more volatile of the two kidnappers says that for them to get away with this they'll need to kill George. McGarrett is on to the fake kidnapping from the start, but he realizes it has suddenly become real and is now racing against time to figure out where the kidnappers have their hideout.

Like I said, the tale of the fake kidnapping gone wrong is an old one, with 1934's Million Dollar Ransom being just one I can think of offhand. It for sure has been done several times since this episode aired. One interesting casting tidbit - Sal Mineo and Harold J. Stone both had supporting roles in Paul Newman's 1956 breakout hit "Somebody Up There Likes Me", although they don't share a single scene together.

Sal Mineo played a struggling singer Bobby George in Honolulu, Hawaii. He gets kidnapped one night. His father is a wealthy hotel owner in New York City. Bobby's kid napping gets coverage and publicity. Bobby and his kidnappers are in on the kidnapping to get publicity for his career. When it goes too far, Bobby is trapped by his greedy kidnappers who turn on him. The episode like all in this series was well crafted for the viewers. Sal Munro gives a worthy performance here.