The remains of an escaped convict are found in a residential sewer, but an examination of the sewer pipes indicates that the murder occurred within prison walls. Brennan insists on solving the crime despite Booth's pleas for her not to overexert herself and the expectant couple experiences a very untraditional arrival of their baby daughter.

An investigation of human remains found in the aftermath of an explosion in a hotel garage hits a snag when the team learn their assumptions about a man's fate are incorrect. Meanwhile, Sweets gets a temporary partner at the FBI.

After Hodgins and Angela are drugged and wake up to a bloody corpse hanging in the canopy of their bed and flower petals around their son Michael's crib, they are forced to believe that Pelant is back for revenge against Hodgins. Although Hodgins wants to go after Pelant directly, Booth knows it's best to work within the system and not go against protocol. Meanwhile, as the Jeffersonian team investigates the corpse, they discover the victim was a Special Forces agent working for the world's biggest supplier of mercenaries, and Angela and Hodgins decide to start an investigation without the rest of the Jeffersonian team for the sake of their family.

When evil tech genius Christopher Pelant returns to toy with the Jeffersonian team in their newest investigation, they discover that the string of murders that have been occurring are tied to FBI agents close to Booth. Meanwhile, as the investigation unfolds, Sweets realizes that the evidence seems all too familiar to him and Brennan starts evaluating her relationship with Booth when signs begin to point to him as a potential target of Pelant's.

The Jeffersonian team investigates the murder of Jamie Delcampo, a member of the Estrellas Locas gang, whose remains were found in a burnt out car. Meanwhile, having taken time off from the FBI in the wake of Pelant's latest assault on the team, Sweets ultimately decides to help with the investigation when he discovers that a young boy from the center where he volunteers is the son of one of the gang members.

The team devises a plan to use a donated cadaver to draw out Pelant; Sweets returns to work and believes Agent Flynn isn't who he seems.

When a CIA informant is found murdered, Booth and CIA Agent Danny Beck (guest star Freddie Prinze Jr.) must work together to track down an Afghani terrorist. Meanwhile, Brennan wants to work more closely with Booth in the field, and the duo must confront the implications of what that means to their family.

Brennan and the team attempt to absolve Booth and get him released from prison. The remains of a man who has been dead for over sixteen years prove to be significant.

Booth goes missing six months after he and Brennan left their careers behind, but a case with ties to the couple pulls Brennan back into the world of forensic analysis, which brings her into contact with a member of Booth's family and Arastoo Vaziri, who's taken the lead at the Jeffersonian in her absence. Meanwhile, the FBI investigate Booth's disappearance, but one agent's tactics are bad for the team's morale.

The team investigates the murder of someone from Booth and Brennan's past. Meanwhile, Aubrey faces a moral dilemma of his own when he discovers his dad is back in the picture.

With Kovac still at large, the team searches for evidence to track him down. After Brennan experiences a setback, the rest of the team must figure out how to find Kovac without her, putting everything she has ever taught them to the test. When all signs point to Kovac having outside help, as well as a hideout, Booth and Brennan go searching for him.