Most good stories start with a fundamental list of ingredients: the initial situation, conflict, complication, climax, suspense, denouement, and conclusion. Great writers sometimes shake up the recipe and add some spice.
Exposition (Initial Situation): Daddy Was a…Demon?
We're introduced to young Merlin, who is growing up without a daddy at the court of his hostile grandpa. Gramps is King of Demetia (southern Wales), and he's convinced that his daughter was impregnated by a demon. Merlin survives his abuse and two attempts on his life before setting the place on fire and trying to run away. Unfortunately, he gets kidnapped by two Bretons who work for Ambrosius, rightful heir to the throne of Britain.
Rising Action (Conflict, Complication): Mithras, Druids, and Engineers—Oh, My
Turns out that Merlin's kidnappers give him a free ride over the English Channel and straight to Ambrosius himself—which is where Merlin wants to be. He has a vision of the hero-god Mithras and wins favor with Ambrosius, who takes him in. Merlin seeks power wherever he can find it, even among the druids. He also learns to be an engineer and works with Ambrosius' men to get ready for the coming war with Vortigern, High King of Britain. Big surprise? Merlin learns that Ambrosius (not a demon) is his daddy.
Climax (Crisis, Turning Point): Of Luck and [Stupid] Kings
Merlin returns to Britain when he's seventeen to collect intel for Ambrosius, who needs to pick a good time to invade and take the crown. Merlin's almost immediately force-marched to Vortigern's court, where the king is having trouble getting the walls of his tower to stand. Merlin reveals the problem and makes his first prophecy: Ambrosius will beat the snot out of Vortigern—which happens. In a second battle, Ambrosius defeats the Saxon warrior, Hengist. Merlin gets a telepathic message about his mother's death, and Ambrosius rides south to be crowned the new High King of Britain.
Falling Action: Not-So-Lucky Star
Ambrosius sends Merlin to Ireland to help Uther defeat the Saxons' allies. He really wants Merlin to "liberate" a sacred stone from the fortress of Killare and bring it back to Stonehenge—they're redecorating. Merlin does this, but on the way home he sees the king-star burning sickly in the sky and knows that his father is dying. Ambrosius has in fact been poisoned, and it's up to Merlin to fix up Stonehenge as a memorial. Uther takes the crown next and immediately gets hung up on Gorlois' wife Ygraine. Merlin and Uther make their way to Cornwall after the coronation so that Uther and Ygraine can hook up and make a new little kinglet.
Resolution (Denouement): He Done You Wrong?
Uther takes his army to Cornwall so that Gorlois will come out of his castle and face them. He doesn't mean to fight Gorlois, really. Instead, Merlin disguises Uther as Gorlois, and they sneak into the backdoor of Tintagel so that Uther can have one night with Ygraine. Uther gets his way, but the plan falls apart: Gorlois attacks early and is slaughtered by Uther's army. Merlin is nearly killed by one of Gorlois' men, and his trusty servant dies. Uther is angry, but it doesn't matter. Merlin has helped the next great king come into being. The king-star is pleased.