Credit: ABC/Richard Foreman Photo: Castle Looks Curious on Castle Season 5, Episode 20, “The Fast and the Furriest”

After a week of tracking “Bigfoot” last Monday, Castle and Beckett are back to their sexy sleuthing ways in an all-new episode tonight that could be pivotal for their relationship and test them in ways that they’ve never been tested before.

Season 5, Episode 21, “The Squab and the Quail” is poised to be loaded with plenty of tense Caskett moments, and we can’t wait to watch it all go down. Tonight’s episode was originally scheduled to air on April 29, but ABC swapped it with the bomb-themed episode, “Still,” in the wake of the Boston Marathon tragedy last week.

Since “Still” will now be airing next week instead, the chronology of Season 5 may be a bit off, but we’re ready for tonight’s episode nonetheless.

The official synopsis reads:

Beckett must protect a charismatic billionaire whose life is in peril, prompting her to ponder her romance with Castle as it reaches a standstill. Meanwhile, Castle begins feeling insecure, so he tries to get the billionaire's case solved quickly.

According to some spoilers, Beckett and Castle’s relationship has reached a plateau, and the “charismatic billionaire” in tonight’s episode will cause B to question her relationship with Castle.

After four years of will-they-or-won’t-they, we have a feeling it’s going to take more than a billionaire to break Caskett up, but this episode still has us pretty anxious. Will you be tuning in tonight? Vote below!