In episode 4 of ABC's "Castle" Season 8, Rick Castle's (Nathan Fillion) weekly campaign to win his wife (Stana Katic) back would continue with a case that proved that the truth does not always set you free. Sometimes, it just gets you killed. What would happen in "What Lies Beneath?"

It all begins with a murder in a church, as Dave Johnson (Jeff Davis) is shot dead while kneeling at the altar to ask for forgiveness for his sins. At first glance, the murdered man appears to be a hapless janitor with no reason for anyone to want him dead. However, Johnson apparently moonlights as writer P.J. Moffat, the author of Castle's favorite novel. Eager to get involved in the case and woo Beckett with his crime solving skills, Castle secures Johnson's wife, Wendy, as a client. 

Meanwhile, Beckett, who promises her mother that she will not be divorcing Castle, spends the episode making headway on the Bracken drug ring. 

Watch Beckett get some motherly advice in episode 4 below:

Then, things get interesting in the Dave Johnson case. Wendy says that her husband was working as a janitor to research a new book about the mafia. However, after Ryan (Seamus Dever) and Esposito (Jon Huertas) track down the mobster who allegedly met with Johnson, they disocover that the mafia does not know a Dave Johnson. They do, on the other hand, know a Jimmy “Two Guns” O’Malley. P.J. Moffat, Jimmy O'Malley -- would the real Dave Johnson please stand up?

Watch Ryan and Esposito uncover the mistaken identity problem in episode 4 below:

After a boozy lunch with a mob hit man, Castle realizes that there is something off about all of Dave Johnson's behavior. He discovers that Johnson was being courted by a pathological liars support group run. Johnson was a bit of a con man and had been meeting with the mob as Jimmy O'Malley to get the skinny on some shady union kickbacks. Also, his janitorial position only came about after he was fired from a City Hall job after breaking into the accounting records. Johnson had been helping a priest at the church where he was murdered embezzle funds from a crooked city account and gather proof to expose the corruption. He hoped that would redeem him for his previous sins as a con man. 

However, that was not what got him killed. After a "Midnight Run" inspired gag to catch whichever city official is responsible for the accounting "errors" in the act, Castle is able to out the mayor. However, he also discovers that the murder was not the work of the corrupt mayor, but Johnson's wife, his client, the whole time! Johnson was murdered for his most crucial lie -- telling Wendy he was really P.J. Moffat. In the end, Johnson was really just a lowly janitor and that truth was too much for Wendy to handle. 

Watch Castle discover the truth in episode 4 below:

Meanwhile, Beckett, who spent most of the episode giving her husband a hard time about various missteps he was making in the case, still refused to give him any info about her side project. She did, however, make time to reveal that she hate's Castle's beloved P.J. Moffat novel. As for Castle and Beckett getting back together, there is always next week, right?

"Castle" airs Mondays at 10 p.m. EDT on ABC.