Ark was the first episode in Series 1.5,it is the first true appearance of the CIA agent known as hotline.This is also the first episode where the interior of the genesis ark was shown on screen.
The doctor materialises on a barren but breathable planet and begins exploring,there is nothing very interesting on the planet but then he notices a large metal capsule and goes over to it and finds it to be dimensionally transcendental;this is the genesis Ark.The doctor begins to explore it long metal corridors,occasionally he thinks aloud as he has no one to talk to.Just behind the doctor we see a dalek pan across the screen.
The scene cuts to a large control room where there are many daleks operating controls,the controls look designed to be operated with human hands;there is also one young humanoid figure helping them.A supreme looking dalek turns to this human and says that they have detected an intruder,Hotline takes a large pocketbook and flicks through it.He explains to the daleks that according to his book the intruder is the doctor but before he is exterminated he must be taken to the cells,when the dalek asks why Hotline replies that he must be interrogated if the daleks are to be victorious.We cut back to the doctor who is muttering to himself that it looks like some sort of time lord prison,many daleks emerge from no where and herd him into a cell.
The daleks leave the doctor alone and he fruitlessly tries to release himself with the sonic screwdriver.After some time Hotline arrives and begins to question the doctor,in the course of this dialogue we get the impression that 666hotline is a villain gloating.During the conversation Hotline explains that the daleks fell out of the void in the genesis ark at the same time the cybermen fell onto London;as none of this has happened to him yet the doctor does not understand any of it.He goes on to say that the daleks are planning to fly the ark from planet to planet and using it as a base to take over them.Hotline's tone becomes softer as he explains that he is working for the celestial intervention agency as the doctor once did and he is working to stop the daleks,he shows the doctor his psychic paper as proof.The doctor agrees to help him and then the mysterious agent teleports to some other part of the ship.
In the console room the daleks victoriously declare that the final repairs have been made and the genesis ark takes flight towards earth.Just as they reach earth and are about to launch their attack the agent signals to the doctor using the psychic paper "NOW" the doctor rips a panel out of his cell wall and activates an emergency button with his fingerprint.This is a security feature which could only be activated when a time lord's double pulse is detected,causing all the Daleks prisoners to be locked in a forcefield for fifteen minutes.In complete control now hotline steers the ark towards a nearby star and sets up an atmospheric shell around the open door,him and the doctor dispose of the daleks by pushing them out and then closing the door.Back in the control room Hotline and the doctor pilot the ark back to the small planet where they found it and head to the doctor's tardis.
Outside the Tardis hotline explains that he will take the genesis ark as his own ship as is foretold in his book and it also says that the doctor must have no memories of these events otherwise future events will be changed.He takes out his psychic paper and uses it to hypnotise the doctor by making him think he sees powerful hypnotic patterns on it and tells him to forget anything he saw here.Hotline then disapears into his new ship and the doctor sets off again in the tardis.