So, what is the story with that 3x01 preview clip? Why all the yelling? Why aren't they wearing vests? What on earth got Kevin Ryan so worked up, calling his old buddy a 'scumbag'? Why are they so quick to think Castle could have done it?

Like many another obsessive Castle fan, I've let that clip get the better of my curiosity, and my patience! So, aided by a few other spoilers picked up along the way, here's my own take on what might have been going on.

I don't own Castle. Alas!

Rating: T, for mild language and situations later on...

Spoilers: Season 3, episode 1

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Son of a . . .

Detective Kevin Ryan glared at the paper in his hand, and cursed under his breath. The article earning the evil eye and expletives was no lead headline – just a paragraph in the "Arts and Culture" section, but the familiar, grinning portrait beside it had caught his eye at once.

Mystery novelist Richard Castle, author of the popular Derrik Storm series and most recently of the runaway best-seller Heat Wave, will be holding a book signing for his newest thriller, Naked Heat, this Thursday from 2:00 to 4:00 at Best Read Books . . .

The rat! He's back in the city, and this is how they find out? He spends all that time tagging along, becoming one of the team, becoming their partner, and then drops them cold?

It was bad enough he ran off for three months without so much as a text message to say, "hey guys, the writing's going well, how's life at the 12th?" It was bad enough he'd run off with his arm around his ex-wife, completely oblivious to what he was doing to the woman he was leaving behind. (Ok, to be fair, Ryan had been oblivious too until Esposito filled him in, but that wasn't the point.)

But this? He's back in the city, holding book signings, and he leaves them to find out from his publicity? It was like breaking up over facebook! Ryan felt like he could spit.

He didn't even notice Esposito reading over his shoulder until a voice six inches from his ear asked, "Does Beckett know?"

Ryan shrugged, and threw the paper down on a countertop. They were supposed to be investigating a stabbing, not reading the paper, but could Ryan help it if some patron of the seedy burlesque club had left the Ledger lying open in the same room as the corpse?

Maybe it shouldn't hurt, but it did. Somewhere in the back of his mind, a little flag was waving, trying to remind Ryan that Castle was just living his life and never promised to check in the moment he crossed city lines. But they'd let Castle in. They'd trusted him, made him a real part of the team. And this is what they get? Was book research all they'd ever been to him after all?

The scumbag...

Esposito was frowning too. He'd put a lot on the line for Castle, trying to open Beckett's eyes to what Writer Boy was really doing there, why he was still hanging around when he had enough research for fifty books. Beckett had finally taken the hint, too, but before she could act on it, off goes Castle with that blonde ex of his, talking about how great it will be spending the summer with her. And just like that, Castle had walked away. He hadn't had to watch the expression in Beckett's eyes as the elevator doors closed on him and Gina. Esposito had seen it, though.

Kate Beckett is our sister. She's family. You don't do that to family.

And here he is, the famous author back again, and the first they hear about their 'partner' is from a note in the Ledger.

Not cool, bro. Not cool.

Esposito hoped Beckett hadn't seen it yet. They'd just finished another tough one, the shooting of a high schooler by another kid not much older, and Beckett had been taking it hard. She didn't need this right now.

But when he glanced back at Beckett's face, her hard, set expression as she leaned over another corpse, Espo knew it was no good. She'd read her morning paper too. That would be the reason for the awkward silences in the bullpen that morning. That would be why she hadn't touched the espresso machine, and had positively glared at both his and Ryan's cups of coffee, and why she'd slammed the squad car's door like she had a grudge against it. Esposito could relate.

I went out on a limb for you, bro. I called you partner. You owed her more. You owed us more.

Just as well, really, that Captain Montgomery picked that moment to call, cutting off a train of thought that was only getting bitterer by the minute.

Beckett said only a few words before snapping the phone shut and starting toward the stairs, waving for the team to follow.

"This vic can wait. There's been a break-in reported in one of the apartments above the club, fourth floor, within the last five minutes. A neighbor saw an adult male, brown hair, black coat, forcing a lock at number 417. She doesn't think the man noticed her. We're closest to the scene…

But Beckett never finished that sentence. With two floors left to climb, there came a distant crash, then another, and a woman's shriek, and then three gunshots… Without so much as a glance at one another, the three detectives were running, bounding up the remaining flights three stairs at a time.

The door to #417 was open, and the lock did look forced, just as they'd been told. Dingy as the halls and stairwells had been – dingy and disreputable, just like the club below – the room they now entered felt more like a chic art gallery. Or, maybe like a gallery after an earthquake. Guns drawn, they cautiously stepped around the toppled furniture, sculptures knocked to the floor, and paintings thrown askew. Yes, an artist lived here . . . or had lived here…

Another crash cued them that they weren't alone. Whoever had fired those shots hadn't counted on cops so close to the scene. He was still in the next room, maybe cleaning up evidence, thinking he had time for his escape, or maybe he was just admiring his handiwork. Maybe he wanted to be certain the woman was dead.

Silently, Beckett motioned to her partners: "watch my back," the gesture said. They nodded.

Three guns were held steady. Three sets of eyes were focused on the door in front of them. They didn't know what, or whom, they'd find, but they were ready.

With one final nod signaling the moment, Beckett kicked open the door.

"NYPD! DOWN! RIGHT NOW!"

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The mind is a curious object. Sometimes it will take in a thousand details all in a glance, and sometimes, one single thought blots out the rest.

There was a body on the bed, its position unnatural, blood from the bullet wounds just visible from the door. A massive painting covered the whole of the wall behind it, and on that towering canvas a face seemed to be wailing, or screaming, over the murdered woman. In this room alone, furniture was still upright, as if the struggle had ended abruptly when the killer crossed the threshold.

There was no room, though, in Beckett's mind, for details like those.

The first thought was only, "Gun!" And instantly, Ryan was firing on the armed supsect, taking no chances with the lives of his team on the line. But Esposito had seen one detail more, and just managed to knock Ryan's shot wide.

It was then that the man in the black coat turned. He yelled, "whoa!" with a grown-up voice but with a little boy's tone that stopped all three dead in their tracks. And then one single detail eclipsed every other thought for Katherine Beckett.

"Castle?"

"Beckett?"

It was almost all Beckett could manage to ask, "What are you doing here?" And Richard Castle's shock could not have been much less. He stuttered, looking from detectives to corpse and back, and gestured about with his hands, searching for a coherent thought, the great writer finally at a loss for words.

Perhaps it was those gestures with the forgotten gun waving about in his hand that snapped the three detectives out of the trance.

"Drop it!"

"Drop it now!"

"Drop the gun!"

Yes, this was Castle. Their friend, they'd thought. Maybe he'd just been using them after all. But right now, there was only room for shock and confusion in Beckett's mind, and for a desperate attempt to stay professional. And for Esposito, and Ryan, there was something more: there was that burning resentment that had been simmering since summer and had come to a head with that morning's discovery. We let you in. We made you our brother. And now, you're the man with the gun.

"Drop it, scumbag!"

It isn't every day a murderer, caught red handed, looks more like a kicked puppy than like a perp. But Ryan's outburst did the trick. Castle set the gun on the ground and found his voice.

"Guys, it's not what it looks like!"

"It never is," said Beckett. "Castle, turn around." She pulled out the handcuffs. "Richard Castle, you are under arrest for murder."