Death ' s Deal ( audio story ) Death ' s Deal was the tenth release of the " Destiny of the Doctor " audio series , produced by Big Finish Productions for AudioGO . Publisher ' s summary . Responding to multiple maydays , the TARDIS lands on the planet of Death ' s Deal , but the distress calls are old , the final echoes of terrified lost souls . This is an exotic world of lethal creatures , nicknamed " the Deadliest Planet in the Galaxy " , and only the brave , foolhardy or greedy would ever dare to visit . Finding themselves stranded among a motley bunch of space - tourists , the Doctor and Donna must lead a struggle for survival against the frenzied wildlife , as they slowly realise that other members of the group have very different agendas . And soon the Doctor learns of an even bigger threat hiding on Death ' s Deal . Somewhere deep below the surface , is something that must never be unearthed . Time is running out , and only an impossible survivor holds the key . Plot . The Doctor gets a distress signal from a merchant ship called the " Caliban " - - and then hundreds of others - - from a planet called Death ' s Deal . Some of the signals are old , as the Doctor points out . Donna insists on helping anyone they can , and they head for the planet . On the surface , they are at first isolated ; but they are soon joined by a newly - landed ship , which turns out to be full of tourists ( some human , some not ) . The group is led by an amphibian tour guide named Hickery Frimms , in the company of an imperious woman named Mistress Qwelleen . It ' s the 49th century , and the planet is called Death ' s Deal , as the distress signals said , and it ' s reputed to be the most dangerous planet in the universe , where you show up , crash , and no one rescues you . Thrill seekers pay small fortunes to come here . While they talk , a huge creature bursts up through the ground — and swallows the TARDIS ! The tourists flee in their ship , leaving a few behind , including Frimms — but the creature attacks and destroys it , before returning underground . Donna and the Doctor are nearly pulled under in its wake , but are pulled back by one of the tourists , an alien that Donna thinks of as a humanoid , walking barnacle , with many tentacles . It gives its name as Krux , a Nimosite from Ceratesh ; he is an anthropologist . Qwelleen takes out her anger on Frimms , who can ' t get them out of this , and takes charge of the group . It consists of Qwelleen , Frimms , Krux , the Doctor , Donna , a human girl named Lyric , and a human space pirate named Tad Groogan . Qwelleen is almost instantly grabbed by a different creature and eaten while Groogan watches . Frimms tells them they are stranded because it is illegal to be here . He tells the Doctor that one ship , belonging to a rival company , will arrive , but not close by ; but between them and the landing site are any number of dangers . As well , Groogan is looking for a lost ship , the " Howling Jupiter " , which crashed here years ago , and may be the reason the planet is off limits . He ' s tracking a signal that is , oddly , in Morse Code ; when Donna translates it , it spells out " Allons - y " . The Doctor realises at once that the message is for him , and joins Groogan in searching . The " Howling Jupiter " is at the edge of a massive coral field , in an arc on which the coral won ' t encroach . The group finds it easily enough , and Groogan goes to investigate , Frimms with him , leaving Lyric to watch the others ; but the Doctor , Donna , and Lyric also go in , on their own , leaving Krux on guard outside . The morse signal leads them to a video message . . . from the Eleventh Doctor , who talks about something under the surface , called slaughter crystals . The Wraith Mining Cartel is coming for the crystals , and must be stopped . To that end , the Eleventh Doctor wants the Tenth to locate a man named Professor Merritt Erskine , who has proof of the crystals ; the Doctor must save Erskine and transmit proof of the crystals ' existence to the Galactic authorities . The Doctor is familiar with the crystals ; he knows they are used for incredibly powerful bombs and weapons , and nearly every planet has banned their extraction . Lyric is confused by how the man can also be the Doctor , but he waves away her questions . On the way out , they meet Groogan and Frimms . The Doctor intends to go into the coral field , despite the danger ; he sends Groogan to get everyone to safety , but Donna and Lyric both insist on staying with the Doctor , prompting everyone else to follow as well . As soon as they go outside , Frimms is killed by another creature . More creatures are approaching , driving them toward the coral field . Donna and Krux fall into a deep hole , somehow surviving . They find a network of tunnels , and flee into them ; the Doctor has no time to get them out , as the creatures are approaching . He gives her a flashlight and the TARDIS key , and sends her to find the TARDIS if she can . The Doctor , Lyric , and Groogan continue on , dodging traps as much as possible . They encounter a wild man , who surprises them and pushes them into a crevice . The Doctor realises that it is Professor Erskine ; and Lyric , overwhelmed , reveals that she is Erskine ' s daughter . He has lost his mind , and imagines himself the master of the entire world ; and he doesn ' t seem to recognise Lyric . He leads them deeper into the crevice . Donna and Krux are still navigating the cavern . Krux realises they are not natural , but excavated ; but by the monstrous creatures , not any intelligent species . They stumble upon a half - rotten , partially - eaten body . They hear a creature approaching through the ground , and run down a random tunnel . Erskine takes his group through a canyon . Lyric reveals that Erskine was a planetary surveyor ; as such , he used to fall on the side of ecologists and protesters in battles with mining and other such interests . He disappeared six years prior . Lyric , after much time , found that Wraith was responsible ; they tricked him into surveying Death ' s Deal , then shot him down — but she never thought he was dead . She admits she used Groogan to get here . They reach a cave , guarded by beasts that Erskine has tamed , and go inside ; they find it is the wreck of Erskine ' s ship , now serving as his home . There are no records to be found — but the Doctor ' s sonic screwdriver agitates Erskine ' s tame creatures and coral garden . He concludes that it ' s the technology from all the crashed ships — specifically the distress signals — that are making the planet deadly ; everything on the planet is agitated by the electronics . Erskine threatens the Doctor with his staff , which is tipped with a slaughter crystal . Donna and Krux are menaced by a massive , wormlike creature , which is chewing through the rock like a tunnelling machine . It traps them at a dead end . Krux , whose species is like a large mollusk , opens his exoskeleton , and takes Donna inside , then hurls himself into the creature . Its simplified digestive system passes them through quickly as Donna holds her breath ; and they make it out the other end . But , more worms are coming , and Krux cannot endure another passage . They hurry on , searching for the TARDIS . Groogan tries to take the valuable crystal from Erskine , but Erskine scratches him with the crystal . Groogan quickly begins to decay as if poisoned , and dies in seconds . The crystals possess a kind of radiation that transmits in lethal doses upon contact with bare skin . Erskine forces Lyric and the Doctor outside . Donna and Krux come upon a deposit of crystals , which is guarded by a maze of deadly coral creatures . The TARDIS is right at the centre of the mass . With the worms behind and the coral ahead , they are trapped . Erskine leads the Doctor and Lyric to a huge crater , which is filled with a gigantic coral creature . He intends to kill them here ; bloodstains indicate he has killed many others . Lyric tries to get him to open the locket he wears , which has pictures of herself and her mother , but he will not ; and he sends his pets to drive them off the cliff . Donna and Krux run for the TARDIS . Krux is attacked by the coral , and injured badly . She uses the flashlight to lure the polyps away ; the coral ' s tentacles accidentally touch the crystal deposit , and begin to die . Donna gets Krux inside the TARDIS , and locks the door . He is amazed by the TARDIS , but assures Donna that he will live if he doesn ' t move . Donna tries to signal the Doctor from the control console . The Doctor receives the signal on his screwdriver , but he drops it as Erskine lunges . Lyric attacks her father , and he drops the staff , but they both go over the edge , landing on a lip of the slope . The Doctor nearly falls , but recovers the screwdriver , and sends a signal back to the TARDIS with it — although using it agitates every creature around them , and causes Erskine ' s pets to fall to their deaths . Erskine has a moment of clarity , and looks at his locket ; he falls to the coral below , but throws the locket to Lyric before he does . The Doctor latches onto Lyric , but they both begin to slip . The TARDIS carries Donna and Krux to the lip of the crater . The Doctor sends her to get a long cable from the console room , and uses it to get himself and Lyric back to the top . Lyric opens the locket . Inside , she finds a microdrive memory device , and gives it to the Doctor . On it are the survey results for the planet ' s crystals , which he sends to the galactic authorities as asked — but the TARDIS sensors reveal there are three automated mining ships approaching . As they are unoccupied , he sends a signal to cause the ships to self - destruct . Immediately afterward , the authorities respond , and initiate security procedures for the planet . The Doctor takes them back to the planet briefly , where things have changed . He reveals that he has stopped all the distress signals , and now the planet is calm . Having patched up Krux , he prepares to leave ; and Lyric and Krux stay behind to meet the rescue team that is coming , and explain everything . Krux intends to return later with an expedition to study the planet ' s biology . Lyric thinks the Doctor failed in his mission , but the Doctor says that the message said to save Erskine — it didn ' t specify " which " Erskine . He gives back the microdrive , and its data . References . " to be added "