chunk: Red October passes near USS Dallas, a Los Angeles class submarine under the command of Cdr. Bart Mancuso, which is patrolling the entrance of a route used by Soviet submarines in the Reykjanes Ridge off Iceland. Dallas hears the sound of the stealth drive but does not identify it as a submarine. Putting information about Ramius' letter together with the subsequent launch of the entire Northern Fleet, Ryan deduces Ramius' plans. The U.S. military reluctantly agrees, while planning for contingencies in case the Soviet Fleet has intentions other than those stated. As tensions rise between the U.S. and Soviet fleets, the crew of Dallas analyze sonar tapes of Red October and finally realize that it is the sound of a new propulsion system. Ryan must contact Ramius to prevent the loss of the submarine and her decisive technology. After it is revealed that Ramius has informed Moscow of his plan for him and his officers to defect, Ryan becomes responsible for shepherding Ramius and his vessel