An invasion of meteorites and an environmental crisis!

A scientific expedition has disappeared from the bed of the Thames Estuary, where a giant meteorite had landed years previously.

Having landed the TARDIS in the same vicinity, the Doctor and Sarah Jane are attacked at night by a vast, roaring creature.

Someting reminds the Doctor of his encounter with the marine denizens of the planet Pesca, but before long his worst fears are confirmed: strange meteorites are landing all over the world, and the Pescaton invasion has begun.

This novel was the only novelization not based on an actual TV episode, but based on an audio play released as an LP "Doctor Who and the Pescatons" (1976), script by Victor Pemberton.