S4·E19 U-509

When a sub is seen off the coast. It appears to be an old German U-Boat from World War II. A message is sent saying that unless their demands are met, they will kill thousands of people. They agree to a meeting and Steve is sent to meet with the person. The person claims that the sub has a cache of nerve gas which when released and depending on the wind will reach a populated area. Oscar decides to send Steve to get into the sub and to try and neutralize the threat. But Steve is captured and is shown the nerve gas. But the Admiral receives information that there is no...