 Ioan Groffudd ably repeats his role as British sea captain Horatio Hornblower in this multi-episode series. This episode opens with the British at peace with the French. Hornblower, as well as many other officers, have been reduced in rank,left on land and are being paid half-wages. This leaves them on very poor-footing and Hornblower has been reduced to pawning his overcoat and his sword to make ends meet. Even with this he is in arrears of payment to his boarding house owner (Barbara Flynn). However, her daughter, Maria (Julia Sawalha) has eyes for Horatio and covers for him. Meanwhile the French under Napoleon is starting to build a military again. Hornblower is given a new command to sail a Frenchman (Greg Wise), who is supposedly opposed to Napoleon, to the shores of France to meet one of his countrymen to obtain information. Instead they encounter a well-established military who capture Hornblower and many of his crew as the result of the cowardice from one of his crew (Christian Coulson), a young seaman who is the nephew of one of the military leaders. A rescue mission is mounted that may be a bit unbelievable but, nonetheless, is full of action. The title references the fact that person or persons may have betrayed the British cause and exposed the British ranks to the French guard and explores the reason for that treason. Returning to England, Hornblower learns his former landlady and her daughter have fallen on hard times. Hornblower offers financial assistance that he can now afford, but because of improprieties in a young lady accepting money from a gentleman, Hornblower suddenly finds himself in an emotional engagement that he may not actually have a genuine interest. Contains lots of naval violence, swordplay, and some gunshots, but most are very discreetly filmed.