Justina Mansell, the youngest daughter of Lord and Lady Mansell, is told that her sister has been invited to visit India, but cannot accept. So Justina jumps at the chance to go in her place. Her aunt arranges for her to be chaperoned aboard ship by the stately Mrs. Arbuthnot, who is travelling with her two daughters and her little terrier, Muffin. Justina is quickly attracted to the good-looking Sir Thomas Watson, who is most attentive and much admires her beauty. When the Arbuthnot ladies succumb to seasickness, Justina takes Muffin for walks along the deck. There she meets the solitary figure of Lord Castleton with his own dog. He knows her father and they strike up a friendship. When Justina is compromised in her cabin by Sir Thomas, even though she has given him no encouragement, she is forced to agree to become engagedl. Lord Castleton is not at all pleased by this turn of events, especially since Justina seems far from happy with her engagement.