ONE of the neatest tricks adopted by Doctor Who is its habit of explaining away historical mysteries as a consequence of alien intervention. So we’ve had Daleks forcing the evacuation of the Mary Celeste, Pyroviles taking a hand in the eruption of Vesuvius and Terileptils starting the Great Fire of London…

The fact that the extraterrestrial impact which wiped out the dinosaurs may play a major role in Earthshock is telegraphed from the start, when the Doctor and his companions discover fossil bones on 25th century Earth. But how the TARDIS crew come to be caught up in this devastating events, and the tragic loss it will cost them as a result, is what makes this one of the most highly-regarded Who stories from the often lacklustre eighties.

After foiling an attempt to blow up the Earth using a hidden bomb, the Doctor traces the source of the device to a space freighter outside the solar system, and discovers a force of Cybermen hidden onboard.

The Time Lord’s old foes intended to use the bomb to wipe out an interstellar alliance conference which is meeting on Earth, and with their initial scheme foiled, rig the freighter to crash instead, locking its navigational controls in place.

While the Doctor and his friends Nyssa and Tegan contend with Cybermen inside the TARDIS, his other companion Adric uses his mathematical skills to try and crack the lock placed around the controls, inadvertently sending the ship jumping in time back to prehistoric Earth, where it remains on a collision course with the planet below…

This 1982 story marked a definite shift in the style of Doctor Who to a more action-packed, grim-and-gritty approach which it was to play up on until BBC1 controller Michael Grade suspended production in 1986, citing the levels of violence as a reason for his actions.

This Target Books adaptation was written by Ian Marter, who played Harry Sullivan in the show, and read by the Fifth Doctor himself, Peter Davison, the strongest acting talent to take on the role during this era of the show. Like some of the other Target novelisations, it isn’t a straightforward adaptation of the events portrayed on screen, and Marter succeeds in adding much-needed depths to some of the minor characters who might otherwise be little more than cannon fodder.