Beyond the Western Sea #2: Lord Kirkle's Money book by Avi

Maura and Patrick have escaped the desperate poverty and danger of leaving home in Ireland to face even greater peril as they continue their daring voyage to the New World with their friend Laurence Kirkle. Aboard ship, they are crowded into the stench-filled pit of steerage, where they come face to face with illness and death, trying their best comfort and protect eight-year-old Bridy, who has lost both her parents. They find themselves at the mercy of fellow passengers--shady characters like Mr. Shagwell, an American in dire need of cash, and the conniving Mr. Clemspool, who sails first-class with young Mr. Grout, haunted by his criminal past. Ahead lies their future in America, fraught with danger and more crisis than they ever anticipated.