'Castle' Season 5 premiere scoop: Castle and Beckett's romance sets the stage for a thrilling year ahead

Our blue Mondays are almost over: "Castle" returns in less than three weeks!

We've seen the premiere, and can promise you this: "After the Storm" is one of "Castle's" most satisfying (inside the bedroom and out) episodes, and it sets the stage for a thrilling season (inside the bedroom and out).

Here's just a hint of what you can look forward to:

The Heat Is On: Don't expect any morning-after regrets between Castle (Nathan Fillion) and Beckett (Stana Katic). As we saw in the recent promo for Season 5, the pair are positively glowing. And both enthusiastically agree that their night of passion was no one-time (or, four-time!) fling. As they get busy making up for lost time, you can count on their transition from colleagues to lovers to be perfectly natural (unlike many fizzled TV pairings) and absolutely adorable.

Our Little Secret: One of the most entertaining aspects of the premiere involves Castle and Beckett's efforts to keep their romance a secret. We're not sure how long they can contain the news (or themselves), but as showrunner Andrew Marlowe told me after the epic Season 4 finale: "Once people get together, there are plenty of fun challenges, relationship obstacles to overcome [and] really uncomfortable, great, wonderful, crazy, challenging moments that they're going to have to face."

New Big Bad: In addition to a brand-new villain, Season 5 introduces one big badass...and her name is Kate Beckett. Emboldened by her updated relationship status, Beckett finds a new confidence -- which she needs to cope with the latest threat from the conspiracy surrounding her mother's murder. How she copes will amaze you -- Beckett does something so shocking and unexpected in the last scene that you'll be more excited about the episodes to come than ever before. We guarantee it.

"Castle" returns Monday, Sept. 24 on ABC. Are you ready?