Starts off with the PCs in a tavern (not cliche) and it is pretty late, so it's pretty empty
The PCs don't know each other, they are just passing by, when this man runs in and says that his son has been taken by this monster and he needs help! If the PCs decide to join (which good or unaligned ones should) then he leads them towards the cave where he last saw it and he says that he shot it with a few arrows when it attacked him and his son while hunting game.
When the PCs enter the cave, they come to a fork, the path leading to the left has a sign of the Great Wizard's Council (ruling faction of the world) in the wall and the right one has claw marks on the floor
when taking the right tunnel, they come across some beetles (a nice little warmup get used to abilities battle) that leak out of the walls
the PCs finally get to the end, where they see a mother bear with 2 cubs
after killing the mom and a cub, the other cub runs to a hole in the floor at the end of the room
the big hole is the actual den, which has the papa bear (with some arrows inbedded in the body) and the boy in critical need of aid
after killing the bear and rescueing the boy, they make a basic heal check thing to stabalise the boy
the other path, to the left, leads to a custom trap, which is like a magic disco floor which has different panels that trigger different traps
after that, they come across this skeleton that has some obvious broken bones, and has an old scroll that says "Great wizard's council...Orcus controls the seas" blah blah
this leads the PCs to go to the Great Wizards Council Island, and on the way they get attacked by Ocrus Submersibles
but thats afterwards
so what do you think.......
Also, I'd have the forgotten Wizards' Lair be found after the boy is found. Maybe he crawled through a place too small for the bears to follow, and wound up at the entrance to the Wizards' Lair. I'd also beef up the Wizards' Lair to include a guardian - maybe a clockwork monster of some sort that the Wizards left behind to keep their lair safe. And of course put some magic treasure in that lair!
Finally, I'd change the name of the God they are invoking from Orcus to ...
Orca, Goddess of the Sea! She is of course served by Killer Whales.
This is fine for a first adventure. If you were running this with a bit more experience behind you, I'd suggest switching out the plot hook for something else. "Please help" is okay, but it's a bit shaky, and the reason why is that none of your players have anything invested in it other than their general sense of decency.
Instead of "a farmer" and "his son", make it one of the players' brother, who's been hunting with the player's nephew. Possibly on land owned by another of the players. Personal connections are what really connect the characters to the world.
Also, your two paths - one leading to bears, one leading to traps - isn't great, seeing as there's a "wrong" answer (the traps), but players don't have any information on which to decide which is right and which is wrong. It's not a meaningful choice. Also, this kind of design involves creating content that your players will only ever see half of - it's inefficient design, and you're better off creating a single linear dungeon, where players see every encounter, but have real and worthwhile choices to make in each of the individual encounters.
Plus, you'll have to tell me how things go with these "Orcus Submersibles". They sound like a very special kind of awesome.
ps my group all at lv 30 were striken down by Orcus, this post is in their memory