|Death place||Atlantic Ocean|
|Spouse||Mary Sue O’Leary|
|Biological father||Jake Lewis|
Matt is the only child of Adam and Britteny Caldwell and develops leukemia around age 12. The various medical tests involved in preparing for a bone marrow transplant show that Adam is a bad match. The tests were the first indication to anyone that Adam wasn't the biological father. It turns out that he is Jake Lewis's biological son, and Jake is an excellent match. The bone marrow transplant is a success and the leukemia is pushed into remission. Matt, Adam and Jake realize that it could come back, however Britteny is convinced that Matt is cured.
The story line of the second book of the series, Blanche Tickle Girl, includes Matt meeting Mary Sue O’Leary in St John's, Newfoundland, then sailing across the Atlantic and back with her. He marries her after she becomes pregnant. Later his leukemia returns, this time causing his death.BTG26
At the time of Matt's death Mary is 6 months pregnant. She returns to her home in Blanche Tickle, and gives birth to a son that she names Matthew, commonly called Matty. She stays in contact with both Adam and Jake.DS3
Matt's death contributes to his mother Britteny's mental instability and results in her commitment to Brookview Residential Care Facility, an expensive private mental hospital. She spends four months there.DS2
The third book of the series, Distant Shores, starts with Adam deciding to divorce Britteny. At the time of the divorce Matt's father is the chief operating officer and vice-chairman of the board of Caldwell-Deerfield Manufacturing company, but he owns virtually none of it.DS3 Jake, his wife Rachel along with their children are still running the Channel Stop at Winchester Harbor.
According to Wes, Diane Caldwell, a Bradford High School Class of 1988 student who died of leukemia while still in ninth grade is not / was not related to Adam or Matt. He said that it was just sheer brain fade that I used that name twice.