This week Doctor Who was on a Western theme, even if they did film the entire episode of “A Town Called Mercy” in sunny Spain. Beware spoilers as the show has only just aired in the U.K. and not yet the U.S.A.

As the behind the scenes feature shows, the cast relished being on the site of so many major Western films.

The episode opens with the Doctor, Amy, and Rory arriving in the American Old West at a Town named Mercy rather than their intended destination, an apparent Grateful Dead concert in 20th or Day of the Dead festival (Dia de los Muertos) in 21st century New Mexico. The town has electric lighting even though it’s roughly a decade too early for that device.

Upon entering the local saloon, the Doctor quickly finds himself grabbed by the townspeople and left for bait for a cyborg that is haunting the town and cutting off its supply route. The cyborg wants “the doctor”.

After being rescued by the local sheriff and brought to the town jail, the Doctor discovers the source of the technological anachronism is in fact the town’s adopted doctor. The doctor is actually an alien named Kahler-Jax whose craft crash landed nearby. Kahler-Jax and his crew were fleeing the cyborg, who was hunting them down. The Doctor comes to learn after gaining entry into Kahler-Jax’s spacecraft that Kahler-Jax was actually something of a futuristic Joseph Mengele who torched countless members of his own race to build a supreme cybor race to eradicate a civil war on his home planet. Initially, Kahler-Jax shows no remorse and defends his action in an ends justifying the means argument leading the Doctor to attempt to turn him over to the cyborg.

Although Rory has no issue with the Doctor’s actions, both Amy and the sheriff protest. The sheriff states that Mercy is a town of second chances and no matter what Kahler-Jax did in the past he has changed, notably saving the town from certain death in a recent cholera epidemic. Amy tells the Doctor that killing people “is not how we roll” and his ruthlessness is due to his traveling alone too much. The doctor changes his mind and pulls Kahler-Jax to safety just in time. As to Amy’s point, in as much as the doctor subsequently reveals that he is now 1,200 years old (97 years older than he was at the end of last season) it would seem that he has been traveling only with the Ponds sporadically.

After a discussion with Kahler-Jax where Kahler-Jax states he fears death because in his belief system he will be made to carry the souls of those he has wronged uphill, the Doctor realizes that Kahler-Jax has tried to redeem himself by doing good in Mercy. The Doctor reflects on these words that clearly have significance in his own life as well. The Doctor then hatches an elaborate plan of diversion to allow Kahler-Jax make a break for his ship and to escape earth thus saving the town from being held hostage.

In the end, Kahler-Jax decides to apologize to the cyborg for his actions and take his own life thereby avoiding any possible retribution the town might have suffered for abetting his escape. The cyborg then becomes the guardian angel of the town looking after it as Kahler-Jax had done.

The Doctor, Rory, and Amy board the TARDIS, and Amy asks to be taken home because the Pond’s friends are going to start to notice them aging from being gone with the Doctor for so long.

One of the largest puzzles of the episode is how much time have Rory and Amy just spent with the Doctor so that their age difference is noticeable back home, and how does this fit with the idea of the Doctor traveling alone for too long?