The London Eye! Fantastic! He never would've thought of it! The Doctor gave Rose a gleefully amazed grin, glad to have been the one dragged off toward danger. Her eager curiosity fueled his own energy, until he thought he might go mad if he stood still a moment longer. He took her hand again and yanked her along the riverside with a triumphant laugh; the laser fire followed them like mosquitoes.
What was his plan, then? Seagulls screeched overhead, and a cargo ship hulked past on the river; somewhere they'd lost their plastic pursuers. They'd come full-stop to the edge of the Do Not Enter signs of the closed Ferris wheel -- but whoever paid attention to signs anyway? The Doctor hopped a fence, jumped down closer to the water and reached up to help Rose do the same. "Pretty much, yah!" he answered her question, and he gave her a wink as he grabbed her hand. He'd barely turned round when he stopped short, and his expression fell in surprise.
Rose was standing in front of them.
Well, it wasn't actually Rose. It looked like Rose, but this Rose was a bit off on her shiny, soulless expression. She wore the same clothes, her hair was in the same style, she even had the same makeup molded creepily into her cold hard face.
Plastic-Rose was pointing a hand at the two, who were pretty much caught between a wall and the water below.
"Well hello!" the Doctor crooned, grinning even as he raised his hands above his head. "You've got better at this, didn't know you could make a copy without an original, very sophisticated, who did your hair?"
"We knew you'd come" Plastic-Rose replied in a slightly flatter version of Rose's own voice. "A strand of her hair was on the boy's jacket. That's all we needed. We'd hoped you would have left her behind."
"DNA replication, brilliant!" The Doctor smiled and nudged Rose (the real one), expecting her to be as shocked and impressed at the Nestene advancements as he was. "Not modest either, I like it."
Plastic-Rose held out her other hand, the one that wasn't loaded. "Give us the key."
The Doctor raised his chin. He said, "No," like a defiant child.
Plastic-Rose's fingers dropped, and the laser whirred as it powered up.