Tegan, Scott, and Kyle, attempt to barricade their progress, but the Cybermen overpower them, killing Kyle and capturing Tegan, and soon the Cybermen control the bridge. Using Tegan to keep the Doctor in check, the Cybermen install a device that locks the controls of the freighter after setting it on warp-speed collision course with Earth, expecting the anti-matter engines will be powerful enough to destroy the Earth. The Cybermen then order the Doctor to take them to his TARDIS to escape, leaving behind Adric, Briggs, and other crewmen. Adric is able to pass the Doctor his gold Badge for Mathematical Excellence before they depart, knowing the Cybermen are allergic to gold. Scott and his men are able to overpower the minimal guard left on the bridge, and Adric immediately starts working to try to undo the control lock. His first attempt causes the ship to jump back in time about 65 million years; the Doctor, monitoring this on the TARDIS, observes that is about the same time of the extinction of the dinosaurs. Adric's second attempt brings the ship out of warp; though still on course to strike Earth, the impact would not be as devastating. Briggs, Scott, and the remaining crew use the opportunity to leave in escape pods. They try to convince Adric to come, but at the last moment, he returns, having another insight on defeating the lock. Scott relays their status to the TARDIS, and the Cyber Leader orders the Cybermen to kill the TARDIS crew, but the Doctor smashes Adric's badge on the Cyber Leader's chestplate, momentarily stunning it and allowing them to disable the Cybermen. The Doctor finds the TARDIS' controls have been damaged, making it impossible to rescue Adric. On the bridge, Adric nears undoing the lock when a weakened Cyberman fires on him, missing him and striking the keyboard, preventing Adric from making any further attempts. The TARDIS crew watches helplessly as the freighter collides with Earth in a massive explosion, killing the dinosaurs and Adric in the process. Production The working title for this story was Sentinel. Although credited as script editor, Antony Root in fact did little or no work on Earthshock. He was credited to avoid Saward, who had by this time replaced him in the job, being credited as such on his own work, which contravened BBC regulations. This was the first Cyberman story since Revenge of the