Karin travels to neutral Switzerland to discover what the Germans are planning under the code name Operation Dusk. Her search centers on a Swiss clockmaker who holds the key to the operation while German agents close in.

This Top Secret broadcast aired on July 23, 1950. It is listed as episode 7 in the archive. NBC Radio Network carried the broadcast. The cast includes Andrew Duggan, Earl Hammond, Ilona Massey, Peter Capell, and Ronald Long. Other credited names include Allan Sloane as writer, Harry W. Junkin as writer, and Fred Collins as announcer.

The surviving recording runs about 29 minutes. Characters credited in this version include Baroness Karen Geza.

A 1950 espionage series starring Ilona Massey as Baroness Karen Gaza, placing its heroine in stories of international intrigue and intelligence work connected with Europe and World War II.