Then it is back to sea aboard one of the new Liberty ships, SS "Seawitch", on a convoy carrying vital war supplies to the Soviet port of Murmansk. She is armed with a 5-inch gun forward and aft, and anti-aircraft guns. A Navy Armed Guard force joins "Seawitch" to operate them. Upon seeing the Navy sailors, the "Seawitch" crew mock their inexperience but soon warm to their military comrades. The Navy personnel also train some of the crew in gunnery, so the Mariners can replace the Navy gunners in case they ever become casualties.