Sam was a born hockey player. Twelve-year-old Sam Parker has dealt with a lot over the past two seasons of hockey - a concussion, a bully, and a divorce. He has overcome all of those challenges, not to mention keeping his grades up at school. Plus, he and his best friend Jill have discovered they have feelings for each other. Things are going well for him. Then, his divorced parents both start dating again, which is weird and makes him a little angry for reasons he can't entirely explain. The worst part might be Breck, the son of the woman his father is dating. Like Sam, Breck is a hockey player. When both of them try out for the same varsity squad, the competition is fierce. Even when the dust settles on tryouts, the rivalry between Sam and Breck runs through the entire season... and not just on the ice. Breck seems to be taking Sam's place in his dad's life and Sam doesn't like that one bit. In hockey, line changes are simple - tired players get off the ice, new players go on. Sam learns that, in life, change is anything but simple... or easy. And the meaning of "family" isn't always the same for everyone. Line Changes is the fourth and final peewee book in the Sam the Hockey Player series.