艾米和罗利的婚姻陷入窘境，此时Daleks将博士及艾米，罗利带到了戴立克的星球，而戴立克却向博士一行人寻求帮助，原因是监禁着犯罪的戴立克开始失去控制，而此时又出现了未知的天才女孩奥斯温...

A prequel to "A Town Called Mercy" was released exclusively onto iTunes, and titled "The Making of The Gunslinger". It depicts the actual making and formation of the Gunslinger, from a normal humanoid body. It also has an explanation of the making of the Gunslinger in voice-over by Kahler-Jex.

Kahler-Jex is in a lab, announcing that "subject 6", Kahler-Tek, has been activated. The Kahler-Tek cyborg raises up his arm weapon and a light emanates from it.