I just watched the movie, then read the following synopsis. It is very different from the movie, so I am assuming it is a synopsis of the book, which preceded the movie and which I didn't read. Charlie is about 18 in the movie (he graduates high school and is planning to start college in the fall) and Sam is 11, before the movie advances 5 years. The details of the car crash below are very different. Charlie agrees to drop Sam off at a friend's house on his way to a party, the last before his friend leaves for boot camp. Charlie is stopped with the wheels turned left, waiting for a lull in the traffic so he can turn left, when a car rear-ends him, sending him into the left lane, where an 18-wheeler then crashes into the passenger side of the car. Charlie becomes the caretaker of the cemetery - not an undertaker. When Tess is "in between," she notices that she can't see her reflection in a window (not the water.) When Charlie doesn't make it back to the cemetery by sunset, because he is looking for Tess and her boat, Sam goes into the light. After Tess's boat flips over, she is not hanging upside down. Charlie finds her lying on nearby rocks. Tess recovers from the boat accident and goes home, before Charlie is let out of the hospital. Charlie doesn't become a paramedic. Charlie goes to the woods by the cemetery to say goodbye to Sam before he and Tess sail around the world. He can no longer see Sam. It's not clear if he can hear him or not. Sam is not upset that Charlie didn't make it back that other night. He says it was time, that crossing over is better than he could have imagined.
Charlie St. Cloud (age 15) and Sam (12) are two brothers with a love so strong, no force can separate them. When their mom leaves Charlie to babysit Sam, they decide to go to watch a 1991 Red Sox baseball game in Boston against the New York Yankees with their pet beagle, Oscar. They "borrow" their neighbor Mrs. Pung's Ford Country Squire. On the way there they cannot decide which CD to listen to. As they cross the General Edwards bridge on the Saugus River, on the way home, Charlie decides to take a look at the moon to see if Sam was right about the moon being larger that night. Charlie does not see an 18-wheeler truck come and they end up tumbling twice crushing Sam along the way. When they are dead, they find themselves close to the cemetery in Marblehead, the town where they live. Sam is scared and Charlie makes a promise that they will never abandon each other. However, Charlie gets resuscitated in an ambulance by a religious paramedic, Florio Ferrente and carries on living.
Five years later, Charlie has grown up and is working at the Marblehead cemetery. Every evening at dusk he goes to a nearby forest where he plays with Sam. Charlie has the gift of seeing ghosts. This serves him well as an undertaker, as he can talk with ghosts.
In the town lives Tess Carroll, a yachtswoman who wants to make a round the world trip. A week prior to her departure, she directs her yacht in to a storm to test it, not listening to her shipsman Tink Weatherbee, who told her not to go into the storm. The storm sucks Tess into its grasp and the ship flips, leaving Tess hanging on upside down. Tess appears at the cemetery where her dad is buried. While regarding her father's memorial, she hears a loud clanging noise, which is Charlie scaring away the geese with his methods of banging trash can covers togeher. She remembers Charlie from high school and wonders if he remembers her. They both talk and Charlie ends up asking Tess to come over for dinner that night. Both are not entirely sure of this arrangement for different reasons. Tess is concerned with the fact that she never really was a true believer in love, and Charlie is worried that this could come in between his promise to him and Sam. The next day while taking a walk with her dog, Bobo, Tess realizes that people ignore her when Bobo comes off his leash and nobody hears her saying to stop him. She then looks into the water and realizes that her reflection is not there. What is more, she can see Sam St. Cloud, the boy who died 13 years ago.
While at lunch the next day after their date, an officer comes in and states that Tess's boat, the Querencia, has gone missing and parts of the ship have been found. Charlie is shocked at the thought that Tess could be dead. He had heard of "middle ground" where spirits would stay until they were ready to pass over to the next level. He had seen many come and go quickly and others who liked to stay like his brother. In the meantime everyone in the town in possession of a boat, including Charlie, explores the harbor in order to look for Tess's body. Charlie questions his sanity because the night they shared together was so real and Tess was full of life. There was no way she could possibly be gone.
Everyone gives up the search, but then Charlie feels that there is one place he has to go. With Sam's help he finds Tess's body. Tess is transported to a hospital where the doctors stabilize her in a deep coma.
A few months later, Charlie decides to quit his job and move on, bidding a final farewell to Sam, now 25 years old from crossing over. He is now a paramedic at Engine 2 on Franklin Street. During his last visit at the hospital Tess wakes up. Charlie remembers how they met, and Charlie tells her the story of how they met and fell in love at Marblehead Cemetery.