Commanded by Lieutenant Commander Graham Butcher, the ship escorted Convoy JW 64 to Murmansk at the beginning of February. On the 7th, "Denbigh Castle" claimed to have shot down a German torpedo bomber. Almost a week later, the ship was torpedoed by "U-992" as the convoy entered the Kola Inlet at 00:13 on 13 February; the corvette's radar had picked up the submarine at a range of , but had not identified her due to the confused radar returns and darkness. The torpedo struck the bow and the crew thought that the ship had struck a mine. The explosion killed eleven ratings and threw the four-inch gun onto the Squid platform behind it. The remaining bow structure sagged downwards, although "Denbigh Castle" was in no danger of sinking. The destroyer transferred her medical officer over and the corvette "Bluebell" came alongside around 00:45 to receive casualties, and Butcher ordered as many ratings aboard her as he thought he could spare. "Bluebell" began towing "Denbigh Castle" at 02:05 and reached a maximum speed of , "Serapis" screening the ships during the tow.