维基：

The story introduces Lalla Ward as the newly-regenerated Romana. The TARDIS lands the Fourth Doctor and Romana on a strangely familiar planet. There, they meet the android Movellans, who are locked in a war with the Daleks. The planet is Skaro, and in a bunker sits an enemy long thought dead — Davros, creator of the Daleks.

The Doctor and Sarah reach Earth and try to warn the research centre about the Kraal invasion before Styggron unleashes his virus.

维基：

The TARDIS materialises in a hostile jungle on the planet Spiridon. Jo sets out alone to find help for the Doctor, who has fallen into a coma. She meets a party of Thals and is left in hiding aboard their crashed spaceship while they go to the Doctor's aid. The Time Lord, now recovered, learns of their mission to destroy a party of Daleks sent here to discover the native Spiridons' secret of invisibility.
Another Thal spaceship crash-lands in the jungle, and the survivors bring news that somewhere on Spiridon there is an army of ten thousand Daleks. Jo meanwhile meets a friendly Spiridon named Wester, who cures a deadly fungus disease that she has contracted.
It transpires that the Daleks' army is frozen in suspended animation in a cavern below their base. The Doctor, with the help of the Thals, explodes a bomb in the cavern wall and thereby causes one of the planet's natural ice volcanoes to erupt, entombing the army in a torrent of liquid ice.
The newly-arrived Dalek Supreme and his aides are left stranded on Spiridon as the Thals steal their ship and the Doctor and Jo depart in the TARDIS.

Intercepted while travelling between Earth and the Ark, the Fourth Doctor and his companions are transported to the planet Skaro on a mission for the Time Lords — to prevent the creation of the Daleks.

英国女孩Jane和Cathy到法国骑车度假。早上，在路上两人因小事争吵，Jane独自骑车先到前面一个村庄等Cathy，Cathy则在路边树林旁休息。Jane等了很长一段时间不见Cathy，便折回原处寻找，可已经不见Cathy，在地上只留下了一只照相机。Jane陷入了恐惧。无助，语言的不通，使Jane不知道谁才是可信的，特别是经过长时间的来回寻找，“夜幕”即将降临…。