Season 1 Episode 13 Hanging By A Moment

On their way to pick up Karen from the airport, Keith and Lucas' car collides with an oncoming vehicle and an unconscious Lucas is left fighting for his life. Having witnessed the accident, Dan races Lucas to the hospital and must acknowledge that Lucas is his son in order to save his life. Meanwhile, a guilt-ridden Peyton decides to tell Brooke about the kiss she and Lucas shared.

Haley and Peyton hang out. 

Keith tells Deb he loves Karen. 

Lucas and Peyton share a secret kiss. 

Haley catches Lucas and Peyton. 

Haley confronts Lucas about him and Peyton, and that it's not fair to Brooke. 

Keith and Lucas get in a car accident on the way to pickup Karen. Dan grabs Lucas from the car and brings him to the hospital. 

Karen hears about the accident.