Cirrus@Austlit

Prague. 1689. Slobeslav Stojespal is attacked by the Nockrauler. He falls unconcious before the creature could kill him.

The Doctor and Peri arrive thinking it's 4240 & rescue Slobeslav and nurse him back to health. They discover that Prague's river, the Vltava, is turning into a black ooze. The Doctor gets Peri to go to the TARDIS to retrieve an adaptor. Peri starts to leave and notices that the city is disappearing. The Doctor knows what's going on, but needs to figure out why its happening. The city is growing out the gloop.

Peri is chased by soldiers on her way back from the TARDIS. She falls into the river and gets out with no memory of who she is or where she is.

The Doctor soon realizes that Peri is now missing and returns to the TARDIS to find out what is going on & discovers the soldiers examining the TARDIS. He demands to be taken to the King. He tries to convince the King to stop building his clock as it powers the Nockrauler. It was what took Prague & brought it outside the normal time & space.

Peri has been taken over by the Nockrauler. The Doctor contained the creature & frees Peri from its clutches. The Doctor & Peri take their leave.'

[The Doctor is the Sixth Doctor.]

Source: drwhoguide.com (http://www.drwhoguide.com/whotrip23.htm). Sighted 20/5/11