老师伊恩和芭芭拉遇到了奇怪的学生苏珊·福尔曼，并且跟随她到一个废品场，遇到了她的祖父——博士，阴差阳错进入了一个警察电话亭，踏上了一段恐惧之旅。

神秘的博士担心老师伊恩·切斯特顿和芭芭拉·赖特会向20世纪地球上的人们泄露他的秘密，于是带着他们和他的孙女苏珊回到了人类历史的黎明时期。在那里，四位旅行者被卷入了失去制造火之秘密的穴居人部落的野蛮政治中……

作为最早人类的囚徒，TARDIS团队被卷入了一场为争夺部落领导权而展开的致命权力游戏中。

TARDIS团队必须为早期人类生火以求生存。但一旦他们成功了，可能就不会被允许离开了！

时间未知，星球未知。TARDIS降落在一个被包围诡异石化森林的钢铁城市中。在那里等待博士的会是什么未知的危险呢？

原来这颗死寂的星球并非无人居住。博士即将遇到他未来最强大的敌人，然而他和他的团队正饱受辐射病的困扰。

时间旅行者们拼命逃离达勒克城，并想方设法阻止一场血腥的大屠杀。

时间旅行者已经成功逃离达勒克的魔掌，但却留下了TARDIS的一个重要零件。要想取回它，就意味着要迫使萨尔人进行一次危险的行动。

伊恩、芭芭拉和萨尔人艰难地穿过洞穴前往达勒克城。他们能及时到达吗？洞穴中是否有可通行的道路？达勒克们又在策划什么？

时间不多了，博士和他的同伴们试图在达勒克消灭斯卡罗星球上的所有生命之前击败他们。

一次神秘的爆炸将TARDIS击落到虚空中。在混乱中，机组人员彼此猜疑。

TARDIS漂泊不定，机组成员相互攻击。只有通过团结合作，他们才能在被毁灭之前找到出路。

由于能量故障，TARDIS团队被困在13世纪的喜马拉雅山脉。旅行者们被迫加入著名探险家马可·波罗的车队，以求生存。但波罗被他们声称TARDIS能够飞行的说法所迷惑，代表忽必烈可汗夺走了它，希望将这样一份神奇的礼物呈现给可汗，以说服他让波罗回到威尼斯。旅行者们被迫陪同波罗穿越亚洲，前往汗的宫廷，但他们多次试图夺回财产的企图都失败了——不仅被波罗挫败，还被战争领主泰甘挫败，后者显然是在执行和平使命，但对处理忽必烈汗的计划完全不同……

泰甘破坏了队伍的水袋，使他们急需新鲜的补给。

博士和苏珊能够提供在TARDIS内部凝结的水汽给马可，从而拯救了小组免于渴死。当小组与泰甘重聚时，旅行者们开始怀疑他正在策划某些事情。

The Doctor's group manage to rescue Barbara from the Mongols but once more Marco remains unaware of Tegana's involvement.

The Doctor and his friends elect to warn Marco of Acomat's attack even though it means losing their chance to gain access to the TARDIS.

The Doctor, Ian and Barbara are forced to surrender to Tegana and Marco, leaving both of them the opportunity to gain possession of the TARDIS.

Tegana finally makes his move to assassinate the Khan, giving the Doctor and his friends an opportunity to thwart his plans and regain the TARDIS.

The alien world of Marinus. Perfect peace has reigned here for decades due to the mind-controlling influence of a machine known as the Conscience. But now a race known as the Voord have developed an immunity and Arbitan, keeper of the machine, has been forced to scatter the vital control keys around the planet. Now he needs the help of the time travellers to get them back - it will be an extraordinary journey, with perils every step of the way...

The Doctor and his friends arrive in the apparently idyllic city of Morphoton but Barbara soon begins to realise there is more to their hosts than meets the eye.

The search for the second key takes the travellers to a jungle where Ian and Barbara come under threat from rapidly growing plants.

Searching for the third key, Ian and Barbara meet with the sinister trapper Vasor before following Susan and the others into a cave system guarded by the mysterious Ice Soldiers.

The group are reunited with the Doctor in the city of Millennius where Ian faces trial for murder after the fourth key is stolen.

The Doctor and his friends must locate the real murderers and the fourth key before heading off for a final confrontation with the Voord

The TARDIS arrives on Earth landing in 16th century Aztec society. Barbara goes off exploring - despite the Doctor's orders not to wander off - and is taken away by the high priest Autloc who believes she is the reincarnation of the goddess Yetaxa. They believe it is a sign that the rains - which are late - will now come. The high priest of sacrifice Tlotoxl recruits Ian to lead their army but he finds he has a rival in Ixta. Ian is less than comfortable with his role when he learns that they are to deliver the human sacrifice to the high priest at the rain ceremony. The Doctor emphasizes that they must not interfere with Aztec rituals, something that does not sit well with Barbara.

Barbara tries to change the course of history - and Ian fights for his life.

While the Doctor tries to find a way back to the TARDIS, Tlotoxl continues to plot Barbara's downfall and sees an opening when Susan questions Aztec custom.

Tlotoxl's machinations result in both Susan and Ian being arrested. With the TARDIS once again trapped inside the tomb, the travellers' only hope for escape lies with Autloc and Cameca.

The 28th century. The TARDIS materialises on a spaceship orbiting a planet known as the Sense-Sphere, whose natives, the Sensorites, have trapped the ship's human crew in a state of paralysis.

The Doctor and his companions are on board an Earth ship trapped in orbit around the Sense-Sphere when it is boarded by the Sensorites, who steal the lock mechanism from the TARDIS.

The Doctor and his companions are escorted to the Sense-Sphere where they attempt to negotiate with the Sensorites for the release of the TARDIS.

With Ian having fallen victim to the Sensorites' plague, the Doctor is desperate to find a cure. But the City Administrator is still determined to rid his world of aliens.

The City Administrator is determined to destroy the Doctor and his friends and his paranoia prevents the Doctor's cure from being distributed.

While the City Administrator's schemes reach their climax, the Doctor and Ian venture into the tunnels under the city to discover the real cause of the Sensorite plague.

The TARDIS lands during the French Revolution, where Ian, Barbara, and Susan become caught up in the politics of the day. When they are arrested and set to be executed, the Doctor must take on the disguise of a public official to try and save their lives.

Susan, Ian and Barbara are sentenced to be guillotined but an encounter with a dying English prisoner may offer Ian a chance of survival.

Susan and Barbara are rescued by Jules and Jean, two members of the escape chain, while the Doctor gains access to the prison by posing as a revolution official.

The Doctor is forced into a meeting with Robespierre while Barbara's attempts to find a physician for Susan result in them being betrayed.

Ian finds himself held prisoner by the treacherous Leon while the Doctor attempts to engineer Susan and Barbara's escape.

Ian finally delivers his message to James Stirling but in order to secure Susan's release he and Barbara are forced into a dangerous spying mission.