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Sphere of Influence was the first story in the audio anthology Susan's War, produced by Big Finish Productions. It was written by Eddie Robson.

Continuing Susan's story after All Hands on Deck, Sphere of Influence marked the first appearance of the Sensorites in a Big Finish audio drama and showed the first meeting of Susan and Ian following their respective departures from TARDIS. It also saw the return of Veklin and Rasmus, two Time Lord characters active in the Time War who have appeared across several ranges.

Publisher's summary[]

Susan’s first mission is one of diplomacy. The Sense-Sphere could prove a valuable ally to Gallifrey.

But she is not the only one who knows the Sensorites of old. Susan will have the support of an old friend.

Ian Chesterton is about to rejoin the adventure he left a lifetime ago!


Susan has entered a Battle TARDIS commanded by Veklin and is scanned to confirm that she is not a Dalek duplicate. The hull of the TARDIS has been breached and the interior is becoming unstable; Daleks are on board and one exterminates Strato, who was on his final incarnation, before Veklin can destroy it and flee to the secondary control room with Susan. The Daleks wipe out the Time Lords in the primary console room and search for the connection to the Eye of Harmony whilst Veklin jettisons the secondary console room to save herself and Susan. She welcomes her to the Time War.

Susan and Veklin land in the Capitol and meet Cardinal Rasmus, who informs them that the Daleks still have control of the TARDIS and have broken into its link to the Eye of Harmony, using it to drain enough of Gallifrey's power to cripple the Time Lords. The Daleks cannot be disconnected and the Eye cannot be shut down without disabling every TARDIS, but control of the TARDIS could be reclaimed using telepathy. Susan suggests the Sensorites, being the most powerful telepaths that she knows and having proven capable of handling Gallifreyan technology when they removed the lock of her grandfather's TARDIS. Rasmus says that they cannot use the Doctor and ask who else was with her during her visit to the Sense Sphere.

Ian Chesterton is on the phone with Barbara when they both hear the sound of a TARDIS materialising. It appears as a refrigerator in front of Ian, who assumes that it is the Doctor. Veklin steps out and tells him to end his call and come with her to help with a diplomatic mission on behalf of Gallifrey, but he declines to help unless she gives him more information; when she mentions a fight against the Daleks, he agrees to join her.

Susan is concerned that the Sensorites will not want to engage themselves in a war, but Rasmus says that agents have gone back in time to establish a diplomatic relationship with them and are now friends of Gallifrey. Veklin arrives with Ian, whom Susan is delighted to see for the first time in more than fifty years and learns that he and Barbara arrived in 1965 and got married. As Barbara did not spend much time on the Sense Sphere and Ian played an important role in getting the Thals to rise against the Daleks on Skaro, he has been chosen to join her.

Susan and Veklin prepare to pilot the Diplomatic TARDIS and discuss the culture of the Sensorites whilst Ian finds a clothes machine to smarten up. Susan is surprised when Veklin implies that protection of the Sense Sphere will be withheld until they can reach an agreement, saying that the Time War should be fought to protect all species.

On the Sense Sphere, the Second Elder informs his colleagues of the First Elder's decision that the delegates will be confined to the palace. When the delegation arrives, he explains to them that the First Elder is in trade talks on the Ood Sphere and that the Investigator will give them a tour of the palace. The Investigator asks them not to leave the palace or speak to anybody that does not have her approval so as to avoid consternation, which Ian believes sounds paranoid. A Guard will be stationed outside of their rooms for their safety.

Veklin goes to the Investigator's office, waiting for her to discuss security arrangements, whilst Susan and Ian wait in their communal area and talk about how the Sensorites have changed since their first meeting, seeming more hostile. Susan tells Ian that she has met the Doctor several times since leaving him and that she is alone now, having lost David and their son. The Investigator finally returns to her office, telling Veklin that there had been concern that news of the delegates' arrival had leaked to the Interior and thus become accessible to all Sensorites.

Susan dreams of the upcoming negotiations, imagining the Second Elder refusing to negotiate until she supplies him with biscuits made from Arcturan moondust. She hears an angry and resentful voice telling her to leave. When she wakes up, she tells Ian and Veklin that the voice was that of a Sensorite threatening her to try to get her off of the Sense Sphere. Ian and Veklin go to speak with the Second Elder whilst Susan rests before the talks; Veklin wonders if the threat was to try to get a Sensorite to look into Susan's mind, which was forbidden, but the Investigator believes that Susan's mind tapped into the Interior and caught random thoughts.

The negotiations begin and the Second Elder expresses the Sensorites' unwillingness to go to war, even for the technology that Susan offers. He explains that the Daleks came to the Sense Sphere before; he and the First Elder met with three Daleks, who asked for materials to repair their damaged ship, but they easily read their minds and saw that they want the materials to build more Daleks. They exploited the Daleks' lack of strength as individuals and, using the full power of the Sense Sphere, caused them to become paranoid and destroy one another. The Second Elder says that his people are safe on this planet and that they will not leave it.

Ian and Veklin are not party to the negotiations and wonder what is happening. Veklin asks Ian to tell Susan to take a tougher stance and tells him that there are two Battle TARDISes orbiting the Sense Sphere to serve as a threat if necessary. They hear the guard hurriedly leave his post for the conference hall and inform the Investigator before heading after him.

The Second Elder says that the War Council have already impressed upon him the threat that the Daleks represent to the entire universe, but remains unswayed by Susan, particularly when she says that the Time Lords tried to prevent the Daleks' creation. The guard bursts into the conference hall and fires at Susan. He misses and Veklin uses a sonic weapon to disable him, after which he is taken to a cell. Ian goes to speak with the Investigator to ask about her opinion whilst Veklin remains to protect Susan.

The Investigator apologises to the Second Elder and offers her resignation, taking full responsibility for the failure to properly vet the Guard but denying any involvement in the attempted assassination. The Second Elder decides that he will consider whether or not to accept her resignation once the delegation has departed and can detect that the Guard's mind is curiously blank. Ian enters the office and asks the Investigator to be honest with him and his colleagues; he tells her about the two Battle TARDISes in order to get her trust and explains that the Guard had overheard him and Veklin discussing this before the attack. The Investigator thanks him.

Veklin becomes suspicious of Susan and decides that she cannot be trusted and must be removed. She fires her staser at her, saying that the Time Lords made a mistake in sending her, but Ian and the Second Elder arrive and come to Susan's help. The Second Elder uses his mental powers to disable Veklin after she refuses to drop her weapon.

The Guard tells the Investigator that he acted alone and did not decide to attack Susan until today. However, he was not aware of the Battle TARDISes as Ian had believed. The Investigator looks into his mind for answers.

The Second Elder invites Susan to the conference hall and asks her to explain what happened with Veklin. She believes that Veklin was being controlled by a Sensorite and invites him to investigate the matter as he is the Guard, but he deems it a matter for Gallifrey. Susan and Ian prepare to leave the Sense Sphere and look for Veklin. They learn from the Investigator that there is an alien influence in the Guard's mind which reached him through the Interior, not having disconnected from it as the Investigator had ordered. Without any proof and believing that the Elders could also be under the influence, she does not plan to bring this to the Elders until the influence has been eradicated. To do this, she needs the delegates to stay.

Ian and the Investigator visit Veklin and advise her to invoke a clause in a local galactic treaty and insist that she is tried on the Sense Sphere, requiring Susan and Ian to remain as witnesses. Veklin agrees and Susan informs the Second Elder, who considers it to be abuse of a technicality. Nonetheless, the Investigator recruits Susan to assist her in the investigation and takes her and Ian to the portal to the Interior.

Susan and Ian enter it and search through the chaos for the mind of the Guard. They enter and see that he is thinking about what he should have done during the attack to be successful. The Guard sees them and fires. They retreat to another mind and find themselves in a Sensorite's fears, namely the burning of the Sense Sphere. In another, they see a ruined city and determine that the alien influence is spreading these images to provoke fear and paranoia. Daleks attack the city.

The Investigator visits Veklin and says that she now feels that the Sensorites are already a part of the Time War.

Susan and Ian see worries of the Time Lords coming to the Sense Sphere and taking the Sensorites away in droves to pacify other worlds. They find themselves in a dark and noisy area, which they realise would be the perfect place to hide something from the Sensorites. With focus, they are able to see what looks like a child's diseased lung; Susan senses that it is part-Sensorite and part-Dalek, a genetically-engineered organism capable of manipulating the Interior and spreading fear. It disappears and Susan and Ian give chase, following it to a memory of the conference hall where it is guarded by Daleks which Susan turn against one another by imagining a host of Sensorites.

Veklin tells the Investigator that she remembers everything that she did but that she was being manipulated. A Sensorite enters with a gun, planning to kill Veklin, but the Investigator wrestles with him and accidentally shoots him. After helping Veklin barricade the door against more Sensorites, the Investigator contacts Susan in the Interior using telepathy and they update one another, realising that Ian going for the parasite was what caused the attack. Ian suggests that Susan sends a message to all Sensorites, but she instead decides to broadcast the sound of his phone to them all so that they will disconnect from the Interior.

Susan and Ian find that the Interior is completely empty and that the parasite has no power, meaning that Susan's plan has worked. They exit the Interior with the parasite, which Ian tosses to the Second Elder after telling him what it is. Susan explains that the Daleks learnt during their visit how dangerous the Sensorites could be and sought to sabotage the Interior. This convinces the Second Elder, who tells them that he will be contacting the Senior Warrior and sending her and her elite troops with Susan and Veklin to Gallifrey.

The Daleks on board the Battle TARDIS find the controls becoming unresponsive, having been taken over by the Sensorites using their mental powers. The ship self-destructs.

Susan and Veklin return Ian to his home moments after he left. Veklin goes to set the controls, Susan saying that she cannot wait for Barbara as she is needed on Gallifrey. She says goodbye and leaves. The front door opens and Ian calls out to Barbara, saying that she will not guess where he has just been.



  • At the time of his recruitment, Ian Chesterton is talking on the phone with Barbara Wright.
  • Rasmus is a cardinal.
  • The War Council send delegates several centuries back into the Sense Sphere's history, creating a long-lasting diplomatic relationship where none previously existed.
  • Ian uses the clothing machine of a TARDIS.
  • Susan, Ian and Veklin are given crystal water.
  • Susan dreams that the Sensorites want cookies made from Arcturan moondust.
  • The Second Sensorite recalls a time in the Sense Sphere's history when a lone group of Daleks discovered the Sphere and attempted to turn it into a new homeworld.



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