The Secret of Cassandra ( audio story ) For the entire guest cast , this is their only " Bernice Summerfield " audio story ; they have all however appeared in other Big Finish audio story productions . Publisher ' s summary . A vicious war between two nations is coming to a head , and the final movements are centred on the sailing ship " Cassandra " . Along with a very strange cargo , " Cassandra " carries Captain Colley , a man with his own sad burden , and the paranoid General Brennan , a woman convinced that her actions will end the war once and for all . Their grim mission goes entirely to plan , until the " Cassandra " gains an extra passenger - a shipwrecked archaeology professor by the name of Bernice Summerfield . Sensing something is very wrong aboard the ship , Bernice ' s snooping brings her close to a terrible truth . Soon , Bernice doesn ' t know who to trust , and she can no longer be sure if anyone is who they claim to be . . . Plot . Bernice is on vacation on the Earth colony , Chosan . Two of the planet ' s continents , Pevana and Calabraxia , are at war with each other . Benny has been stranded on a desert island for two days after her boat was shot down because she was drifting into enemy territory . The captain of Cassandra sees her and insists on picking her up despite his only passenger ' s protests . Benny wakes up on the ship . It is a high tech vessel despite the exterior looking like a 17th century sailing ship . The ship is full automated , thus there is no crew . The ship also refers to the captain as " Dad " . The only other passenger , General Hannah Brennan , fears that Benny is a spy . Benny and Captain Damien Colley discuss the war . Colley is tired of the war . His daughter , the original Cassandra , designed the ship ' s AI , but was killed in the war . The shock of their daughter ' s death slowly killed his wife as well . Meanwhile , we learn that Brennan is holding a prisoner named Sheen in the cargo hold . Benny contacts a nearby Pevenan ship and tells them about the prisoner . Brennan continues to suffer from extreme headaches and loses consciousness . Benny attempts to let Sheen free , but he doesn ' t seem to desire escape . She eventually takes him to the deck , although this confuses the ship ' s AI , as she was originally unaware of his presence on board . The man then powers up one of the ship ' s staser cannons , which he uses to blow up a ship full of his own people . Brennan reluctantly admits that she worked undercover as a Pevenan for over a year . Sheen was the head of a project to develop a superweapon capable of destroying the entire Calabraxian continent , but Brennan kidnapped him and is taking him to Calabraxia for interrogation . Sheen admits he is responsible for Brennan ' s headaches . Her memories had been blocked , and it causes pain when she tries to remember something about Sheen . Sheen ' s eyes are covered in cataracts , due to an operation that turned him into the walking , living bomb which will destroy Calabraxia in ten hours ' time . Cassandra removed the memory block from Brennan ' s mind . Colley reveals that the whole time he was trying to avenge his daughter ' s death by killing the Calabraxians . Sheen then comes out with an even more shocking revelation , he is in fact the original Cassandra . She transferred her mind into the manufactured body of Sheen in order to continue working on the weapon . Upset and unable to handle this knowledge , Colley then shoots Sheen . In order to dismantle the bomb inside Sheen , Cassandra uploads her intelligence into Sheen ' s body . She is able to do this because Sheen ' s AI network and her own were designed by the same person . References . " to be added "