The Silent Stars Go By ( novel ) The Silent Stars Go By is a hardcover book that marked the return of the Ice Warrior s . It was the last novel to feature Amy Pond and Rory Williams . Publisher ' s summary . 2011 BBC Books edition . " Things have to get worse before they can get better . Trouble is , I think they ' re about to get a lot worse . As worse as worse can be . And then some . " For centuries the Morphan s have worked . With no help from other worlds , they subsist on the food they can grow and that ' s little enough . But their purpose , their whole life is to maintain the machines that will one day make their world as habitable as old Earth . Life used to be hard . Now as their crops fail , livestock sickens , and the temperature drops , it ' s becoming impossible . This year ' s winter festival won ' t be the usual celebration . It ' s not a time for optimism or hope – and it ' s not a time to welcome unexpected guests . The Doctor , Amy and Rory find a society breaking apart under the strain . Tensions are mounting , old rivalries are coming to the fore , people are dying . . . And then the Doctor ' s old enemies the Ice Warrior s make their move . With the cold - hearted threat of invasion , the real battle for survival begins . Or does it ? The Doctor begins to suspect that behind everything lies a deadlier , and even more chilling danger . . . 2013 BBC Books edition . The winter festival is approaching for the hardy colony of Morphans , but no one is in the mood to celebrate . They ' re trying to build a new life on a cold new world , but each year gets harder and harder . It ' s almost as if some dark force is working against them . Then three mysterious travellers arrive out of the midwinter night , one of them claiming to be a doctor . Are they bringing the gift of salvation or doom ? And what else might be lurking out there , about to wake up ? Plot . Instead of returning Amy and Rory to Leadworth for Christmas as he had promised , the Doctor accidentally lands the TARDIS on an Earth - like planet during winter . While Rory returns to the TARDIS to get a heavier coat , the Doctor and Amy meet the inhabitants of the planet , called Morphan s , who capture them as they are convinced the Doctor ' s psychic paper is a conjure which is banned by their religion . A young woman named Arabel " Bel " Flurrish believes they are connected to her missing sister Vesta , who disappeared the previous night . The Doctor denies that they know anything about Vesta and gains Bel ' s trust ; he uses his sonic screwdriver to unlock their cage and the three sneak out from the council of Morphans to look for Vesta . Bel tells the Doctor that they are colonists on the planet , named Hereafter , from Earth . The past few years the winters have grown colder , and this year livestock has disappeared in addition to Vesta , suggesting that there is something out there which is eating them for food . The Doctor , Amy , and Bel find they have been followed by a young Morphan named Samewell Crook , who chastises Bel for releasing the Doctor and Amy as he believes her sister will be found by the council , and threatens to go back and report the incident . Because of this , the Doctor decides he will allow Samewell to come with them . They come across footprints intersecting with another set of footprints and soon find blood in the snow ; however , this belongs to a sheep , as Samewell soon finds a sheep bone which he easily recognises . Rory , meanwhile , finds the Doctor and Amy gone and glimpses menacing figures in the distance which he runs away from . He runs into a group of Morphans , who are also looking for Vesta and who plan to take him captive . However , they see a " green thing " which the Morphans attempt to fight , but t defeats them with deadly energy blasts , and Rory escapes . Rory eventually takes refuge in an abanoed building , but an unknown figure hits him over the head with a mallet and knocks him out . When he regains consciousness Rory discovers that it is Vesta Flurrish , and gains her trust . Vesta tells him she was going to put flowers on her father ' s grave that morning when she ran into one of the " green things " and took shelter in the building . A Morphan finds them and brings them back to the council , who are initially suspicious of Rory , but they accept him . The Doctor , Amy , Bel , and Samewell see a spaceship - like object in the sky , and the Doctor explains that an invasion of the plane has been going on for quite a while . One of the " green things " , which the Doctor identifies as an Ice Warrior , appears . The Doctor interferes with their weapons with his sonic screwdriver , giving them time to escape . They take refuge in a small building , where the Doctor explains to Amy that the Ice Warriors are probably seeking a new home as their home planet , Mars , is gone , as is the Earth and the solar system . Amy is separated and then attacked by rat - like creatures ; the Doctor uses a high - pitched sound from his screwdriver to render them unconscious and explains they are genetically engineered rats made by the Morphans ' terraforming system and are responsible for the dead livestock . Exploring the terraforming plant , the Doctor finds a device which is able to transport holograms of them to the assembly hall when Rory , Vesta , and the other Morphans are . He tells Rory his plan : to reset the terraforming plants which will restore Hereafter ' s climate and drive the Ice Warriors out . However , the terraforming system is very complicated and the Doctor believes the " Guide " the Morphans speak of as their religious figure may be referring to a guide for the terraforming . Amy , Bel , and Samewell escape from the Ice Warriors who interrupted them , but they hold and interrogate the Doctor . He convinces them that what they are doing is not honourable , a trait they value . Meanwhile , Rory discovers he and Vesta were not talking about the same thing earlier ; she did not run away from an Ice Warrior but a monster . The Doctor realises that the Warriors ' sabotage of the terraforming system has led to the creation of this " transhuman " . A transhuman orders the Morphans to let him see the Guide , and the Doctor ' s hologram appears and reveals that the Morphans have essentially been preparing Hereafter for their ancestors : elite people who believed they were destined to live and are in suspended animation in the terraforming plant , waiting for the Morphans to prepare the planet for them . The Doctor and the transhuman reveal that once this is done , the Morphans will be eaten by these people . Transhumans and Ice Warriors bring Amy , Bel , and Samewell to the Doctor , but the two species turn against each other . As they are fighting the Doctor instructs Rory to let him view the Guide ' s information , and he uses the information to stop the transhumans . He convinces the Ice Warriors to leave honourably , and offers a planet nearby he knows they will settle in . Before returning to the TARDIS to take Amy and Rory home for Christmas , he informs the Morphans that he reset the Guide to make it more user - friendly , and the will have the option to choose when they let their ancestors out , if at all .