Merlin is the most exciting TV series I've ever watched. The first episode drew me in, so if the first episode does not interest you, likely the other episodes won't interest you either. If you like the legend of King Arthur, fantasy, sword fighting, a castle, many strange events, the existence of knights, dragons, sorcerers, witches, trolls, druids, and other mythical creatures, you will surely enjoy this series.
Merlin is a boy who possesses magic, yet feels like he has no place to belong to in the world, so his mother sends him to Camelot, to live with her friend named Gaius. Gaius is an old physician to the royal family of Camelot and is one of the few people trusted with Merlin's secret, that Merlin is a warlock. In Camelot, anyone caught using magic or is accused of as being a sorcerer is executed.
Somehow or another, Merlin finds himself as the servant of Prince Arthur after saving Arthur's life. Merlin hears voices in his head, and discovers that there's a dragon living underneath the city. It is the last dragon that lives. King Uther chained it there as a lesson to others that practise magic. Many years ago, King Uther also rid the city of any magical creatures or anyone that practised magic by executing them.
The dragon has lived for thousands of years and has much wisdom. It tells Merlin that his destiny goes hand in hand with Arthur's, and that Merlin is to protect Arthur for the future of Camelot. Because when Prince Arthur is king, magic will once again be accepted in the land.
Arthur and Merlin go on different adventures, and we see the friendship between them form. Many times, while still concealing that he has magic, Merlin must save the life of Prince Arthur because of the many dangers that exist. Every episode stands alone, there isn't any tension most of the time that goes into the next episode.