The Duke of Dominoes ( short story ) The Duke of Dominoes was the third story in the anthology " Decalog " . It was written by Marc Platt . It featured the Fourth Doctor and Sarah Jane Smith . Summary . The Master ' s plans have gone wrong . He has been in Chicago for two months . He had gathered the shards of the Godhead and made a deal with Havuri - sss - Cazcim of Blue Profundis . He knows where the Thought Core is . However , his TARDIS has been stolen , so now he is stuck on Earth . As Sam Kulisa drives the Master to his hotel , they notice that there are few police in the streets . When they reach the hotel , they understand why . There are police waiting outside the hotel entrance , so the Master sneaks in through the kitchen . In his rooms , he finds his secretary , Margie del Monsalvat , talking with police chief Mulligan but not giving him any answers . Mulligan questions the Master , but gets little information . The Master suggests that Mulligan is in the pay of his rival , Joe Clementi , but instead of offering more than Clementi pays , hypnotises Mulligan instead . After Mulligan leaves , the Master receives a message from Havuri - sss - Cazcim , who accuses him of deceiving his people . As the Master and Margie watch the transmission , a star - like light approaches Havuri - sss - Cazcim ' s location and destroys the planet . Margie drives the Master to the Wainwright Museum and learns what he ' s been doing the last two months : he ' s been trying to figure out how to steal a chunk of tekrite , which is actually the Thought Core . They are accosted by Wainwright , who explains to them the nature of the Godhead and its dangerous power . She is from the future , the end of time , and her people destroyed the Godhead to prevent its use . Her purpose is to guard the Core . When the Master tells her he has gathered the shards of the Godhead and intends to unite them with the Core , she tells him the Core is self - aware and is using , not just him , but also Margie , who has been coming to the museum before the Master started doing so . Suddenly , Margie shoots Wainwright with the Tissue Compression Eliminator , which the Master thought was in his stolen TARDIS . Clementi and his men arrive , and the Master learns Clementi is working for Margie . Clementi ' s men grab the Master , but he is able to escape . He leaves the museum , but he is mugged , losing his money and his watch . He did , however , manage to grab the armilla , the device that Wainwright had been using to keep control of the Core . The Master ends up at the Mission Hall , where he spends the next four days helping to make soup and keeping silent . On the fourth day , hearing a voice in his head , he goes back to the museum and climbs up to a window on the first floor . Inside he sees Margie , Clementi and his men trying to get the Core . They spot him and try to kill him , shooting him as he runs away . He notices a star - like light approaching the museum , and realises it ' s his stolen TARDIS , under the control of the Core . It starts shooting at Clementi ' s men . The Master runs back to the Mission Hall and retrieves the armilla from his mattress . It is starting to sweat mercury , so he needs a container for it . He finds a phial of holy water and empties it . As he is letting drops of mercury fall into the phial , Father Sherrin walks in on him . He allows the Master to take the phial , saying the holy water is fake , and gives him the watch that he lost , but the Master kills him and leaves . Some of the mercury lies on the floor next to Sherrin ' s body . As the Master leaves the mission , he sees people running in panic . The statue of Abraham Lincoln from the museum is walking down the street towards him , Margie riding on its arm and carrying the Core . Clementi and his men are behind them . The Master ' s TARDIS also arrives . When they reach the mission , Margie tells the Master that the Godhead has a failsafe — it needs a mind to control it , and it wants his mind . The Master runs back inside as the statue smashes parts of the building looking for him . It grabs him , and he sets his watch to emit sound at a frequency that destroys the statue and part of the building . As the Master is buried under debris , he hears a horrifyingly familiar sound . The Doctor ' s TARDIS materialises on top of him , and though he doesn ' t recognise the voice , he knows it ' s the Doctor and one of his companions . They look around and discover the phial of mercury , which the Master had hidden in a coffee pot . It turns out to be just what they needed , as the TARDIS needs mercury for the fluid link . They take the mercury and leave . The Master is confronted by Margie and Clementi . However , the animated body of Sherrin appears , covered in mercury . Now in control of the Godhead and the Core , he flies out into the sky and away from Earth . The Master heads for his TARDIS and leaves .