Charlie Hunnam and Idris Elba head the cast in director Guillermo del Toro’s epic sci-fi slugfest.

Imagine Transformers versus Godzilla and you will have an idea of the titanic scraps that await as gigantic fighting robots battle even more colossal alien monsters.

It sounds simple enough, but del Toro needs a complex back-story to manoeuvre his antagonists into place.

The alien beasts, known as Kaijus (a Japanese word meaning ‘strange creature’), have emerged through a breach in the Pacific Ocean that has opened a portal to another dimension, and they quickly set about laying spectacular waste to the cities on the ocean’s rim.

In response, the threatened nations create giant fighting robots called Jaegers (German for ‘hunter’) to repel the invaders. Controlled by pilot duos, the Jaegers are initially successful, but as the years pass the alien menace grows, threatening to overwhelm the planet’s defences.

Humanity’s last hope lies with burnt-out veteran Hunnam and an untested rookie (Rinko Kinkuchi).

The film looks awesome, as you would expect from del Toro, maker of Blade II and the Hellboy movies, and it’s to Hunnam, Kinkuchi and Elba’s credit that, despite their thinly drawn characters, they make their mark amid the overwhelming CGI action.