The adventure begins with the party's arrival at a small village called Greenest. The village is being attacked by a group of kobolds and the party is quickly drawn into the fray. After dispatching the kobolds, the party is approached by a representative of the village who asks them to help protect the village from further attacks.
The party agrees to help and sets out to patrol the village perimeter. After a few hours of boredom, the party is attacked by a group of giants. After a tough battle, the party defeats the giants and is hailed as heroes by the villagers.
The party is then approached by the village elder who asks them to investigate some strange happenings in the nearby cave. The party agrees and sets out for the cave.
Inside the cave, the party encounters a group of goblins who are quickly dispatched. Further in, the party encounters a strange creature that is immune to all damage. After a long and frustrating battle, the party is forced to retreat.
Back in the village, the party rests and regroups. They then set out again for the cave, this time better prepared for the creature. After a tough battle, they finally manage to kill it.
Further into the cave, the party finds a group of kobolds who are mining for something. The kobolds attack the party, but are quickly dispatched. The party then finds a strange magical ore that is emitting a strange aura.
The party decides to take the ore back to the village elder to see if he can identify it. On the way back, the party is attacked by a group of bandits. After a fierce battle, the party defeats the bandits and returns to the village.
The elder is unable to identify the ore, but he does know of a wizard who might be able to help. The party sets out for the wizard's tower.
Inside the tower, the party encounters the wizard who is guarded by a group of golems. After a tough battle, the party defeats the golems and the wizard. The wizard is able to identify the ore as a powerful magical substance.
The party then decides to take the ore back to the village to sell it. On the way back, the party is attacked by a group of kobolds. After a quick battle, the party dispatches the kobolds and returns to the village.
The party sells the ore to the village elder for a hefty sum of money and is hailed as heroes once again. The adventure ends here, but the party can stay in the village to help protect it from further attacks or set out to find more adventure.
The above is a basic outline for a dungeons and dragons adventure for a party of level 2 characters. You can use this as a starting point and flesh it out as you see fit.