A giant prehistoric sea monster (65 feet tall standing on its hind legs) is released from its underwater home by a volcanic eruption and caught off the coast of Ireland by adventurous partners Joe Ryan (Bill Travers) and Sam Slade (William Sylvester) who were salvaging for sunken treasure.
They place the monster – named Gorgo – on display in a London circus and Londoners think they’re on to something big – until its even more enormous mother comes to rescue it.
Mama is 250 feet tall, and she trundles up the Thames – having overturned a Navy destroyer sent to intercept her – and breaks Tower Bridge in two, tosses aside Big Ben and the Houses of Parliament, and demolishes Piccadilly Circus.
Attacks by jets, flamethrowers and missiles are turned aside by her scaly armour and her captive infant is eventually freed, leaving Mother Gorgo and child to make their way triumphantly back through the stricken city towards the sea – with the best wishes of most members of the viewing audience.
Good special effects (produced by boffin Tom Howard from the Godzilla school), and seeing London ravaged by a monster is a nice change from Tokyo or New York.
All from the acclaimed director, Eugène Lourié (Que?).