Monsters of rock: How Metallica became one of the biggest bands on the planet

In the summer of 1990 the biggest heavy metal band in the world stood at a crossroads. Metallica, who headline Slane Castle this weekend, had entered the new decade goliaths within the metal scene. But they were also, they feared, hurtling towards a dead end. Having conquered metal, where did they go next?

This existential crisis was unfolding in the shadow of the death of their bass player and early driving force Cliff Burton. He was just 24 when, in 1986, Metallica’s tourbus skidded off a road in southern Sweden, having apparently struck black ice. He was flung through a window, dying almost instantly.