Hadley Sullivan
Hadley Sullivan is the 17-year-old protagonist of the novel. Her story begins by being four minutes late for a flight to London to become a bridesmaid in a wedding she has no interest in even knowing about. Following the divorce from Hadley’s mother, her father is marrying a bride barely older than Hadley (although actually, she is in her thirties). The collective result of a series of minor delays, those four minutes will prove to significantly alter her destiny as a consequence of having to take a later flight.
Determining that she will never so much as lay eyes on her soon-to-be stepmother following the ceremony even at the cost of losing contact with her father, Hadley settles in for a long and depressing trip across the Atlantic. By the time the plane finally reaches London, however, she is barely aware she's been in the air that long.
Oliver
Oliver is a British teenager who happens to be booked onto that later flight. Hadley is initially apprehensive but eventually engages him in conversation. She learns that he is attending Yale on a summer research grant to study the fermentation of mayonnaise. The flight becomes a dazzling real-life version of a romantic comedy—or maybe a Disney romance—as Hadley and Oliver hit it on cylinders even though he is merely flying home for a vacation while she is flying into her worst nightmare.
Upon arriving at the airport in London, Oliver is forced to enter the customs line for passengers from EU nations while Hadley enters the line for “all others.” The plan is to meet at the end, but he is nowhere to be seen when she is finally done. As it turns out, however, Oliver is about as forthright in his explanation of what he is in America to study as he is about the real reason he is returning to London. In fact, Hadley is not the only one flying into a nightmare.
Hadley’s Dad
The engine driving the story is the upcoming wedding of Hadley’s dad to the student with whom he had an affair. Hadley has changed the ID of her father’s phone number to “The Professor” because the word “Dad” is just a little too unpleasant. The affair with the student resulted in the collapse of the marriage of her parents and so Hadley’s father is not exactly her favorite person in the world. Nevertheless, she feels obligated to attend the wedding.
Since the affair took place while her father was on a teaching assignment at Oxford University in England, the occasion of the wedding will be the first time Hadley has seen her father since the divorce. All her dad really wants is for her to make an effort to get to know his new wife with no pressure placed upon his daughter to treat his new wife like a mother.
Charlotte
Charlotte is the “other woman” that Hadley tells her dad she has no real desire to watch him dance with just before she escapes the wedding reception in an attempt to track down Oliver. Hadley has constructed a persona in her mind for Charlotte that is barely a step above wicked stepmother. The immediate reality that Hadley confronts upon finally being in the same room as his father’s bride for the first time turns out to be infinitely worse. The key phrase is spoken by another party, but explicitly refers to Charlotte's delicate condition: “nine months.” And with those two words, Hadley realizes she isn’t just gaining a stepmother, but soon enough a stepbrother. Or, worse, a stepsister.
