Doctor Who and the Pescatons

The Doctor and Sarah Jane arrive on a beach by the Thames Estuary at night, and discover a metallic seaweed there. The Doctor consults with Professor Emerson, who says that three expeditions to recover a recent meteorite from the bottom of the estuary have all vanished. The Doctor goes diving and is attacked by something that wraps itself around him, but then lets him go. The meteorite is really a wrecked spaceship buried under the estuary. The Doctor believes it is a Pescaton ship. The Pescatons are carcharhinidae, or deep water sharks. The experts scoff at this, until one comes out of the Thames and makes its way to London Zoo in search of salt water. The Doctor confronts it in the Aquarium, where it dies and disintegrates. That night, more meteorites land in the Thames.

London is invaded. The Doctor recalls his visit to planet Pesca, where he fell down a chasm into a cavern and met Zor, the Pescaton leader. Zor said he would use the Doctor to find a new home; Pesca was drying out and falling towards its sun. Zor used his hypnotic powers on the Doctor, who fought back and escaped. Back in London, Sarah Jane finds an abandoned baby while the military shoot rounds at the invading Pescatons with no effect. The Doctor distracts a Pescaton by singing "Hello, Dolly!" and doing a dance so that Sarah Jane can get away with the child. Finally the Pescatons fall back to the salt water, except for one trapped in a London Underground tunnel. The Doctor and Sarah Jane search for it, and the Doctor plays a piccolo to calm his nerves. The Pescaton retreats at the sound. Professor Emerson helps the Doctor build a high frequency sound trap inside a sewer, and Zor is lured there to be destroyed as the planet Pesca disintegrates in its orbit. Without Zor to control it, the Pescaton invasion ends.

• The Pescatons title listing at the Internet Speculative Fiction Database
• On Target — The Pescatons