"Don't do this," River says. "Let's walk away from this."

"Are you giving me an argument or an order?"

"I'm saying don't do this."

Bit late for that. With most of her entourage left to guard the Tardis, Kovarian has gathered her human captains about her to take her safely to her escape ship. She could come out and face me when she thought I was doing the same, but now she's afraid. It's all going. It's all, as River said herself, in motion. "I'm sorry, my love."

She says nothing because she knows I'm not, not really. Sorry she feels that way, certainly, but not sorry about what we're doing.

With her four man escort armed and ready, you can hear Kovarian's heels all over Stormcage, echoing down around the galleries, even over the rumble of a new stellar storm gathering outside. It is a sound which does absolutely nothing for me. Scout's honour. They see her straight to the old emergency launch on the third circle. They kept it, I think, in case of prison riots or takeovers. Stormcage is isolated, cut-off; if anything ever happened, theoretically they could have fired somebody back to the Justice Department to ask for help.

Unless, of course, all the power was switched off to negate the electromanipulation abilities of a certain race of tall pale gents. Then they wouldn't have been able to do much at all.

My only consolation in that deep guilt is that Kovarian too is going absolutely nowhere. They reach the port to find Captain Francesca Holly leaning against it, holding in the safety clip of a Falklands era grenade.

"Anybody know how to get the pin back into one of these?" The lead guard, on Kovarian's left, steps forward and places the muzzle of his rifle to her temple. "At this range you'll take the both of us out, mister."

"Get out of the way, princess?"

"Okay." She steps aside. There on the airlock door is an explosive of a different kind all together, a little silver egg with two magnetic braces holding it up. "Now, you can get in and out alright, that's fine. But I wouldn't take off, if I were you. See this little guy?" So that she can point, she moves the grenade into her other hand. Even all this way away, over the scanner, I hear every other person in the hallway catch their breath. "Any major pressure change and he's liable to blow your airlock door. Seriously, though, guys, this pin? Any ideas? Oh, no, hold it, I think I've got it. I think…"

She releases the safety clip. Kovarian puts herself very, very quickly behind her captains as Frankie holds it to her ear, listening carefully.

After five seconds, when nothing happens, "Yeah, I got it." The closest thing I've ever seen to a smile flits over her face. "The Doctor respectfully requests that you join him in Bracewell's former office. It was the only place he could remember how to get to."

Not strictly true. I could get to Cell Forty-Six in my sleep. I'm just not sure if River's been here or not yet, so it would have been hit and miss for symbolic significance.

"You want me to kill her?" asks that first and bravest of the captains, still poised to shoot Holly.

She looks up at him and pulls the pin back out of the grenade. "Or you could go see the Doctor, huh?"

I swear to you, here and now, I will never ever tire of watching Kovarian steel herself. The way she prepares for me, puts all her personal fear and apprehension away in a cupboard somewhere and becomes cold. At this point in her life, she's still just pretending, but she'll get used to it. It'll become natural to her. Someday soon she'll just stay cold and it'll be more than she deserves.

She makes a point of saying, in front of Frankie, "To my office, then."

I suspected as much. The space is very much cooler and cleaner than it was as Bracewell's. There are files instead of books, and no clutter, no photographs, no executive desk toys. There's a waste-basket with nothing in it and a gun mounted under the desk. Where there used to be a false projector window showing the Lake District of Old Earth, there's just a blank wall. No pretence, no illusion. No hope.

Still, River lingers over there, as though if she only looks hard enough…

"What's the matter, River?"

"Walk away."

"Stop saying that."

"It's not too late, my love, we can be gone before she gets here. Call it all off and just go."

"Why?" I reach out, take her by the wrist and pull her over to me. "Why, River? Give me one good reason. You must have dozens, it's all over your face, but just give me one. One precious gem out of the whole future that some kindly creature must have spread out before you. Just the one. Why have we been criss-crossing timestreams and I'm not even aware of it? Convince me, River, don't just tell me."

"You never learn. We don't lie to you, Doctor, none of us do." She breaks off because I'm laughing, "Not even me. We don't lie to you. Walk away."

"Convince me!"

"I'll kill you!" It's sudden, a break. A weight she couldn't bear up anymore. That's what she's known all this time, and it hurts her just as much to let it go as it did to hold it back.

"Pardon? Couldn't hear you over all the déjà vu, love."

"Walk away, or I'll kill you."

"You too? Now you, I could believe it of. You? Yes. Maybe."

I turn my chair back towards Bracewell's desk. River says no more. Paces once or twice, and for a moment, somewhere in the midst of it all, there's a damp, ragged edge to her breathing, but that doesn't last. It's not going to get her anywhere. The crocodile tears never are a good idea.

Anyway, it really is too late now. They're nearly here now. And River knows that, no matter how she might be feeling or what's going through her mind, she's going to have to be strong for this bit.

Down the hall from the office, the entourage suddenly stops. It's the first and bravest of the captains again. He stops, and with a few deft steps, puts himself and his rifle between Kovarian and the other guards.

"I'm sorry, ma'am," he says. "I wasn't sure until just now, so I couldn't say anything. But one of these guys is an imposter."

"I beg your pardon?" she balks.

That's me. Right in her inner circle at the drop of a hat, and her none the wiser. The Captain goes on, "He's been planting explosives everywhere we go, and I can't think why else he'd be doing that except on behalf of that damn Doctor, ma'am. You go on and stall him. I'll finish up here and start clearing the bombs."

Oh no. They're onto me, and my wicked plan. Gasp. Shock-horror. Egad.

Kovarian, breathless at having had such a close call, and with a gratitude I'll probably never see again; "Thank you, Captain… I'm sorry, I don't know your name."

"Harkness. And it's my pleasure. Good luck in there, Madame Kovarian."

Again, before she can tear her eyes off him and run off to meet little old me, "Thank you…"

"Arrogant sod," I mutter, "How does he do it?"

River, bitterly, "Oh, don't worry, you're well on your way." I swivel my chair just enough to look up at her. Heels in the hallway, just enough time. One last exchange, you and I, dear. Convince me. One way or the other, River, convince me. She leans down, one hand on either arm. Close enough to be warm and to whisper, "There are limits, my love."

Close enough for me to turn her cheek fast and hard against my lips and tell her, "Only for the limited, sweetie."