"Castle" Season 6 premiere episode, "Valkyrie," began on a high note for "Castle" fans and ended on a cliff-hanger that Rick Castle (Nathan Fillion) may have only a day more to live. "Castle" Season 5 finale had ended on a shocked face of Kate Beckett (Stana Katic) because Castle got down on his knees and proposed to her.

"Katherine Houghton Beckett, will you marry me?" Castle asked Beckett. And, finally we know that the answer is a big "YES."

The job offer at Washington D.C is once in a lifetime opportunity for Kate Beckett ( Stana Katic). She tells Castle that it is her shot and if she does not take it up, she will regret it. Kate isn't sure about Castle's reaction and whether he will change his mind after hearing her decision.

Castle is in a completely understanding mood and is serious about making the relationship work. He assures Kate that he is not proposing to her because he wants to keep Beckett in the same city or because he fears losing her. Castle tells Beckett that I'm proposing because, "I cannot imagine my life without you" and, if things get difficult they need to figure it out and he is assuming that Kate is willing to figure that out with him.

"In that case, Richard Edgar Alexander Rodgers Rick Castle, Yes ... yes ... I'll marry you," Kate finally says. And, she asks "We're going to able to make this work, right." Castle assures that they are going to be great and D.C is going to be great, as well. The two kiss, happily.

The episode takes a leap of two months and Kate is chasing a criminal in Washington D.C. The man uses a woman as a shield to get away and asks Kate to put down her gun. Kate puts the gun down and also a round shaped, shiny object, which is a harmless explosive. The man gets caught but the woman turns out to be one of his accomplices and she shoots at Kate.

Kate falls down on the ground but thankfully, it is mock training exercise and we see Kate's new boss Rachel McCord (Lisa Edelstein). Kate gets reprimanded for not being more alert and the new boss asks her to step-up her game and that intel can be sometime wrong and that "you've to use" your "judgement and "instinct."

Castle returns home from a West Coast book tour -- 12 cities in eleven days -- and finds two surprises waiting for him. Alexis (Molly Quinn) has returned home from Costa Rica, a week before the scheduled date and she has brought with her a new boyfriend, Pi (Myko Olivier).

Pi says to Castle, "Mr C, awesome to meet you." Castle does not share the same feeling and wonders aloud to his mother whether Pi is staying at their place and if he is staying in Alexis' room. The over-protective father is not very amused by the latest development and he intervenes the kissing between Pi and Alexis.

Before, Castle can have a talk with Alexis, Beckett calls up to inform that she won't be able to come over for the weekend. We come to know that Castle and Beckett have not seen each other in six weeks. But, Beckett cannot do anything about it as a priority case has come up and she promises to make-up to him, next time.

Beckett cannot come but Castle has the time and resources to land in Washington D.C to be with Beckett. The two have a steamy reunion - the viewers do not get much glimpse of that. In the morning, Castle gets to know that Kate is working on something classified and his curiosity meter gets alerted. He wants to dig, further but Beckett does not share much information. But, Castle finds a page of the classfied document that Beckett leaves behind, unknowingly.

The curiosity does kill Castle as he calls-up Esposito (Jon Huertas) and Ryan (Seamus Dever) for consultation and tells them that he is working on his new novel and need the details for that. His description to them is about a crime involving national security that needs to be investigated using only a photo, and there is a serial number. Castle tells the duo that he is the "ruggedly, handsome everyman" and not the spy in the book. Ryan and Esposito find that the serial number is that of transformer that was sabotaged two days, ago and which the feds are investigating (Beckett's backyard).

Beckett and McCord reach a Golf club to find more information about the crime, only to find Castle already there, asking very much the same question. McCord reprimands Castle and tells him that she will slap obstruction charges against him and kick out Beckett if she finds him snooping around, again.

"She (McCord) is not invited to the wedding," Castle tells Beckett, and that he didn't think he will get caught. He promises to not look, further and not to fiddle with the investigation when Beckett tells him that he will be in jail and she will get fired. However, he informs her that there was a man who came in a gold sedan before the incident. Someone clicks Castle's photos. Beckett and McCord are looking for an inscription system that was stolen and are unable to find the man who stole it. They zero-in on his girl-friend.

Castle gets abducted by the same man who Beckett and McCord think is the person behind the crime. At the gun-point, Castle is asked to sit in the car (the gold sedan). The man wants to know what kind of information Feds have and if they know about "Valkyrie."

The man soon drops dead and the car crashes and when Beckett and McCord reach the accident site, they are perplexed to find Castle, again. Castle is put under-arrest. The top fed bosses know he did not do any crime but it is their way of teaching him a small lesson so that he keeps his nose out of feds business. Castle goes back home and finds Pi preparing dinner, papaya steak as he is a fruitarian.

Castle cannot keep his nose out of the feds business for too long. He starts researching on his own after Esposito tells him about possible connection of "Valkyrie" with the top secret military ghost base. Before Castle is able to make much headway, the feds arrest him again. This time from his home.

He is back at the interrogation cell at Feds office in Washington D.C. This time it's a serious matter related to him. Beckett tells him that the dead man in the car died of a chemical that was in the car system and that Castle's blood also has that chemical.

He has only less than a day to live, Beckett tells Castle.

The episode is to be continued, next week.