What is a summary of The Guardian by Nicholas Sparks?

The Guardian, by Nicholas Sparks, is a romantic thriller featuring 29-year-old widow Julie Barenson. Four years prior, Julie's young husband Jim died of cancer. Before his death, he wrote her a letter promising to always protect her and encouraging her to find someone new who would make her happy. Julie's protection came in the form of a Great Dane puppy Jim had arranged to be delivered to her the Christmas Day after he had passed away. Julie felt grateful for the dog, named Singer, because she knew that Jim understood the dog would become part of the family Julie never really had, other than Jim, and help her move on. Singer certainly did help her move forward with her life, and now that four years have passed, she no longer feels the "searing ache" she used to when she thought of her husband soon after his death (p. 1). She also feels ready to try and find someone new to make her happy.

Julie begins dating Richard Franklin, whom she finds interesting and enjoys the amount of attention he devotes to her, especially his surprise visits to her beauty salon where she works as a hairdresser. However, she begins feeling smothered by his attention, and Singer growls in Richards' presence. Meanwhile, Mike Harris, Julie's late husband's best friend, who has had a crush on Julie for years, finally gets the nerve to ask her out. When Julie begins dating Mike, she tells Richard she is no longer interested. Soon, the reader learns just how obsessed Richard is with Julie and that Richard's childhood has helped him develop into a very dangerous person.

Richard begins stalking Julie, and a police investigation uncovers that Richard Franklin is actually the identity of a missing man. Richard's identity had been stolen by Robert Bonham, who had also been missing since the disappearance of Robert's own wife. Robert had murdered both his wife and Richard and assumed Richard's identity.

As Richard's stalking continues, Mike and Julie run for their lives, but Richard is able to find their hideout. In the end, Singer, on the brink of death after having been poisoned by Richard, finds enough strength to attack Richard and defend Julie long enough for the police to arrive.