"If the Sergeant doesn't stop those trains, D-Day goes down the drain!"

The speaker was Colonel Fairbairn, special OSS advisor to General Omar Bradley, at a tense meeting of SHAEF only days before the planned Normandy invasion. Thus began yet another do-or-die mission of the man called The Sergeant – C. J. Mahoney (Code Name: Parrot), a big, brawling career G.I. Mahoney was an almost perfect killing machine with an incredible knack for languages ... and the Army's heavyweight champion foul-up.

His assignment was to stop the personnel and supply trains crafty General Erwin Rommel had lined up to checkmate the assault he knew would come on Omaha Beach. His first try failed when a key bridge wouldn't blow. Now, with Gestapo Colonel Richter on his trail, it's last-chance time as Mahoney and a handful of maquis steal an explosives-laden train and head for a fateful rendezvous in a tunnel of death!