TRAPPED IN THE MURKY waters of the Fetch Lake, Putta felt his throat and chest burning. Both twins were clutching his limbs now with astonishing strength.

I can’t…I can’t…

He could feel himself beginning to lose his grip on the world.

There’s got to be…The Doctor would think of something…Bryony would…I got this far.

And, with his last remnants of strength, Putta unscrewed the flask and let the psy fluid escape into the water. He let it do what it always did – enhance the psychic fields of all available entities in the vicinity and render them more known to each other, or suitably calibrated detection devices.

It had been all he could think of to do and – suddenly, massively – all he could think of increased. He even – for a very brief period – awoke the dormant telekinetic abilities he shared with sixty-seven per cent of Yakts. And this meant that, at his most despairing, he became stronger than he ever had been.

The twins were disorientated by his surge of energy and also perhaps by this burst of ambient psychons. Putta was just able to break free from them and strike out towards the surface of the lake.

Once his head broke through the water he gasped, spluttered and flailed in a very unheroic manner, but he still felt immensely glad to be alive.

Which was just before he felt entirely horrified. The Doctor had wanted the psy fluid. And Putta had just emptied it out into a lake.

That may not have been absolutely the right thing to do.