The Queen Charlotte is taking on passengers for her maiden voyage from her berth on the Hudson River, and her first destination is Southampton. But some of the 100 guests are taking a 90-day trip around the world. Among those on this ultra-luxury cruise are Alvirah and Willy Meehan, who are celebrating their 45th wedding anniversary. This couple has appeared in Mary Higgins Clark's books before. After winning the lottery, Willy quit his job as a plumber, and Alvirah was no longer a cleaning lady, managing to secure a job writing for a newspaper.

Also on the boat are a fascinating group of people, all of whom have secrets and plans to do harm to some fellow passengers. The first murder is committed by a wife who stands to cash in a five-million-dollar insurance policy after she pushes her husband over the railing on their patio. The second murder is that of Lady Emily Haywood, or "Lady Em," as she is called. The old woman has a priceless emerald necklace known as the "Cleopatra Necklace," which is believed to have belonged to Cleopatra, and she intends to donate it to the Smithsonian. Readers then are told about her personal assistant of 20 years and the secrets she has.

"Some will think that ALL BY MYSELF, ALONE is a 'cozy' or 'locked-room mystery' because it takes place on a ship, isolated from the outside world until their first stop on Long Island."

Part of the entertainment on this luxury cruise are lectures by people who are well known in their fields. They are there to speak on their various specialties, including Professor Henry Longworth, "a renowned expert on Shakespeare," and Celia Kilbride, "a gemologist who could find a flaw in any gemstone." She, too, has a secret, but it doesn't stay that way for long. She had been engaged to Steven Thorne, a hedge fund manager who stole money from his customers. He told Peoplemagazinethat Celia knew all about the scam. That information is a main topic of gossip among the guests on the cruise, even though it is not true.

After her presentation, Lady Em asks Celia to talk about the legend of the necklace being cursed. Celia is not comfortable with this request, but since Lady Em insists, she says, "After being ordered to wear the necklace at sea while being taken prisoner to Rome, Cleopatra put a curse on it: 'Whoever wears this necklace to sea will not live to see the shore.'" She makes sure that her audience knows that legends are only that and should not be taken seriously.

Another guest on the ship is Devon Michaelson, who "heard everything and missed nothing…. The 'Man with One Thousand Faces' was well known to Interpol. His brazen thefts, which had occurred in seven countries, were an embarrassment…. The thief liked to taunt Interpol about his accomplishments…” His is more or less an open secret since the police and the captain of the cruiser knew he was aboard. He is after Cleopatra’s necklace. Readers will have to pay attention to him, as he is a very shifty character.

Some will think that ALL BY MYSELF, ALONE is a "cozy" or "locked-room mystery" because it takes place on a ship, isolated from the outside world until their first stop on Long Island. Then the police must be called and the bodies removed from the ship's morgue. And it seems as though the world swoops down on the passengers, the crew and the boat itself.