The series follows Castle as he uses his insights into human behavior to help Beckett solve crimes. Castle is often able to come up with creative and unconventional solutions to cases, which often frustrates Beckett but ultimately leads to success. The two characters have a close relationship, which often borders on romantic, but they never officially become a couple until the eighth and final season.
In addition to Castle and Beckett, the series also features several other characters, including Captain Victoria Gates (Penny Johnson Jerald), Detective Javier Esposito (Jon Huertas), and Detective Kevin Ryan (Seamus Dever). These characters often assist Castle and Beckett in solving crimes, and they also provide comic relief.
Castle is a light-hearted and entertaining crime drama that has been praised for its likable characters and clever writing. The series has won numerous awards, including two People's Choice Awards for Favorite TV Drama.