Air date: 1/28/10

A human skeleton is found in a ditch on an old Civil War battleground and is covered in clay making it difficult for the team to determine the cause of death. Booth's brother Jared returns from his travels with a new girlfriend, in which he intends to marry. Feeling suspicious, Booth performs a background check on her, which angers his brother. They later reconcile, where Jared tells him they do not keep secrets from each other and asks him to be his best man.

The Devil in the Details

Air date: 2/4/10

Booth and Brennan investigate the remains of a man found in a church with horns and a vestigial tail, resembling a demon. The case leads them to Havenhurst Sanitarium, where the victim was committed to as he had schizophrenia. The case causes intern Arastoo Vaziri to talk about his beliefs of good and evil, including revealing a secret from his past about serving in Iraq where he was forced to kill someone.

The Bones on the Blue Line

Air date: 4/1/10

While Dr. Sweets is on a subway train, a stranger tells him he has just been cured of leukemia, then the train is thrown off its tracks as a water main breaks, causing havoc inside the train leading to death of the man who had just been cured of cancer. The accident exposes a skeleton that was caused by the flooding, leading Booth and Brennan to investigate. With the release of Brennan's second book, a reporter interviews her for a Japanese magazine. Sweets deals with the near-death experience feeling it was a message to live his life fully, leading him to propose to his girlfriend Daisy.

The Parts in the Sum of the Whole

Air date: 4/8/10

Booth and Brennan set the record straight regarding when they first met as Dr. Sweets has completed his book detailing the relationship between the two which he believes they are in love. Sweets is worried that this information could invalidate his book so he has them tell the story of when they first met, which happened six years earlier. The story includes how Angela came to work for Brennan at the Jeffersonian; the first time Brennan, Hodgins and her grad student Zack worked on fresh remains; and that Booth and Brennan shared a kiss during their first case and Brennan decided not to spend the night with him as they were both drunk. After solving their first case, the two argue where Brennan storms off telling Booth she hates him because she thinks he is a bully and never wants to work with him again. It took over a year for them to be in the same room again and work together. After completing the story, Sweets feels one of them needs to take a chance to confess their feelings, he encourages Booth. Once outside, Booth kisses her and confesses his love for Brennan, wanting to take a chance at a relationship. But she denies because she thinks she can't change and doesn't have a open heart like he does. Booth tells her that he has to move on then, finding someone that will love him. Both then walk off together.