Natural speed please, as if you were telling this scary story to children. A wee Scottish accent would be a bonus! ;)
A long long time ago, wee Jimmy McFadden was going home along the loch when he met a beautiful horse. Its skin was smooth, like the skin of a seal and its mane was dripping with water. Jimmy McFadden approached and touched the horse; but it wasn’t warm at all: in fact its skin felt very very cold. ¬ The boy realised that this was not a real horse, but a malevolent animal. Unfortunately, it was too late to run away. The power of the water-horse was irresistible and Jimmy McFadden was like hypnotised: he climbed on the horse’s back, and the horse galloped into the water of the loch, taking the young boy with him, and drowning him. Jimmy was never seen again.
My accent isn't too genuine but I hope it may be enough for your purposes!