Beware, Princess Elizabeth is a novel by historical writer Carolyn Meyer. Princess Elizabeth is the youngest daughter of King Henry VIII. Upon his death, Elizabeth's world begins a roller coaster ride that will end with her ascension to the throne of England. The path begins with romance, treachery, and death, teaching Elizabeth the pitfalls of allowing herself to become too close to anyone, especially men with ambition for power and wealth. In the end, Elizabeth knows she can only rely on herself and it is this belief that will one day make her a long reigning and successful queen. Beware, Princess Elizabeth is a historical novel that gives young audience the perfect insight into what it must have been like to be third in line for the throne of England for young Princess Elizabeth Tudor.

Elizabeth is told of the death of her father, King Henry VIII, three days after his death. Together with her younger brother, Edward, Elizabeth goes to London for her father's funeral and her brother's coronation. Upon arriving, Elizabeth and Edward are greeted by Queen Catherine, Henry's sixth wife, and Thomas Seymour, Edward's uncle on his mother's side. Elizabeth notices a connection between Thomas and Catherine that causes her some concern and her fears are confirmed later when her governess, Kat, tells her that there are rumors of a romantic connection between Catherine and Thomas.

After witnessing her brother's coronation, Elizabeth is asked to live with the dowager queen, Catherine, at her estates in London. Elizabeth is thrilled to live with her stepmother. Elizabeth's delight only increases when she realizes that Thomas Seymour is a regular visitor at Catherine's home. As Elizabeth's adoration for Thomas grows it is fueled by Kat's comments that Thomas might be interested in marrying Elizabeth when she grows closer to an acceptable marrying age. However, Elizabeth soon learns that Thomas and Catherine have married in secret. Despite this, Elizabeth continues her crush on Thomas, but is soon banished from Catherine's life when she is seen kissing Thomas. Soon after, Catherine gives birth to a daughter and dies from a subsequent infection.

Elizabeth learns a short time after Catherine's death that Thomas has been arrested for attempting to kidnap the king. It is thought that Thomas had plans to marry Elizabeth without her brother's permission and that several of Elizabeth's servants were in on the plot. Kat and several others are arrested and Elizabeth is submitted to questioning day and night for several months. Finally Elizabeth is cleared of wrong doing, but Thomas is executed. A short time later, Thomas' brother, Edward, is also arrested for treason and replaced as the lord protector by John Dudley.

Kat is eventually released from the Tower of London and returned to Elizabeth. Elizabeth lives a fairly quiet life for the next few years, attempting to appear as a devoted sister in her brother's court while avoiding his and Lord Dudley's attempts to arrange a marriage for her. Elizabeth's brother then becomes ill and Lord Dudley begins to plot to make his own son king. Lord Dudley has Lady Jane Grey declared King Edward's successor shortly after her marriage to Lord Dudley's younger son. However, the common people of England will not accept Lady Jane as their queen and join Mary in the fight to regain her throne.

Mary is a tyrannical queen. Due to her fanatical belief in the Catholic Church, attempts to make Catholicism the only religion in England and burn all who will not conform to her wishes. Mary is an older woman, desperate for love, and has two hysterical pregnancies during her reign. Mary is also frightened of being pushed from the throne by Elizabeth or her conspirators, so Mary places Elizabeth in the Tower of London, eventually releasing her but never reinstating her freedom. When Mary dies, she reluctantly makes Elizabeth her successor as their father had originally intended.