What kind of game would you like to see? 4 hours and 3rd level is perfect for a dungeon like Lost Mines of Phandelver's (beginner/basic) which has really easy pre-made 3rd level characters.
If you'd like a social/exploration intensive challenge - you could pit them against a Doppleganger (CR3) who is causing havoc having infiltrated the local soldiery, adventurer's guild, or thieves' guild.
If you want a mix with some options, I suggest a "defend the caravan" scenario that:
*Opens guarding caravan travelling between two small pop towns - social
*Engages combat as the caravan is ambushed by goblins - combat (quick/easy)
*Party can be tasked by interesting caravan NPC to stop the goblins! - social
*Find the goblins (interrogate, track, etc) and find the goblin's caves - explore
*Ambush and infiltrate the goblin's lair - combat
*Goblin leaders saw them coming a mile away and counter-ambush/trap party - TWIST
*Explore from buried cave entrance to find way out - explore
*Discover and engage the goblin leader (I prefer true neutral human) with some interesting combat/social interaction
If you'd like a social/exploration intensive challenge - you could pit them against a Doppleganger (CR3) who is causing havoc having infiltrated the local soldiery, adventurer's guild, or thieves' guild.
If you want a mix with some options, I suggest a "defend the caravan" scenario that:
*Opens guarding caravan travelling between two small pop towns - social
*Engages combat as the caravan is ambushed by goblins - combat (quick/easy)
*Party can be tasked by interesting caravan NPC to stop the goblins! - social
*Find the goblins (interrogate, track, etc) and find the goblin's caves - explore
*Ambush and infiltrate the goblin's lair - combat
*Goblin leaders saw them coming a mile away and counter-ambush/trap party - TWIST
*Explore from buried cave entrance to find way out - explore
*Discover and engage the goblin leader (I prefer true neutral human) with some interesting combat/social interaction
