From the introduction:
While the Rebels are stationed on Hoth, a mysterious condition affects all comlinks. The Rebels are unable to communicate with each other or with offworld bases. For some reason, a pair of comlinks the team possesses are unaffected. While they are relaxing between missions, a Rebel agent, a Cerean female, finds the heroes and discovers the working comlinks. Knowing how much of an asset they could be, she sends them to two dangerous locations: the Rebel base on Hoth and an Imperial Star Destroyer where a Rebel sympathizer can feed fleet information to Rebel Command. Because of the extreme secrecy required, the team will be given disguises and a familiar loaned transport. Also, they must land well away from the base on Hoth itself to avoid rousing suspicion, trekking across the arctic wastes to the base. Once that is done, if the team is up to it, they can help locate the saboteur. Wideband jamming is out of character for the Emperor, so there must be a network of civilians organizing the strategy. The Rebels have little to spare in the way of credits, but would offer a fair amount of training and influence to anyone who can help them with this problem.