After a few generic case episodes and a mini hiatus, Castle returns with an episode that strikes at the very heart of Beckett's (Stana Katic) quest for justice in her mother's murder.

At this stage in the game, anything pertaining to Senator William Bracken (Jack Coleman) strikes close to home for the entire team, so it's easy to forgive them a few blunders early on.

With all they've been through, finding A) Melanie Rodger's body burnt beyond recognition and B) a phone record that leads directly to Bracken seem like obvious indicators of foul play on Bracken's part. Even interviewing the victim's sister and speaking with the hotel manager where Bracken and Melanie held clandestine meetings all appear to implicate Bracken. It's not until they locate the parking garage where she was killed and discover the meaning behind "XT3" that their perspective on the case takes a sharp left turn.

Taking two people with the history that Bracken and Beckett have and making them work on the same side makes for nothing short of riveting television. The threatening looks that pass between them during their first meeting while others are around are rivaled only by the private words exchanged by Beckett and Bracken afterward.

But despite her orders to protect him, the further the case progresses, the more difficult it is for Beckett to separate her duty from her past. The discovery of a pair of threatening letters from a possible suspect lead to a nice moral quandary for Beckett, granting viewers yet another excellent scene between Beckett and Dr. Carter Burke (Michael Dorn). Cutting to commercial just as she moves a match close to the evidence is a nice touch, too.

But in the end, Kate proves her mettle far outweighs that of her rival. With the case all but slammed shut on Robert McManus (Brett Rickaby) it would've been easy for her to shove the whole emotional mess back in a safe corner in her mind and move on. But she can't, even at Castle's (Nathan Fillion) urging.

Ever churning, her mind can't help but mull over the case, and the longer she stews, the more convinced she is that all of the evidence against McManus came just a little too easy. While much of the journey is one Kate must walk alone, this is a great scene between Katic and Fillion, culminating in Beckett's decision to risk her career to save a man she loathes.

The risk pays off and in the end, Bracken owes her one for saving his life, opening up some very interesting possibilities for the future. All in all, a solid episode in the Beckett-Bracken story arc.

Castle airs Mondays @10pm on ABC.