The Party for their various reasons either as a group or individuals have been travelling with a merchant by the name of Samuel Jakes along a winding route through several villages as he sells his wares and gathers new stock, during the stay at the last visited village Samuels current wares are primarily kegs of various sizes of the local Mulled Cider.

 Due to the long trips between towns and Samuel's reluctance to eat into profits (Literally in several cases) it has been two weeks of travelling rations and hard tack for the players and the pair of guards that accompany Samuel. The final destination that Samuel and players are travelling to should be a centre of trade such as a large market town or port whichever is more suitable for your setting.

For the last two weeks you all have been travelling with a merchant by the name of Samuel Jakes through several of the local villages, while the old merchant is cheerful and talkative company his somewhat tight fisted habits and desire to travel quickly to make his deadlines mean that you've been force to subside mostly on bland travelling rations and water, having little time to stay in a tavern during your trips through the local villages as you all travel on to you final destination. 
The dust of the road and the summer heat been bad enough, the urge to drink is almost made worst by the fact that Samuels latest cargo is several kegs of Mulled Cider, though as you follow the long roads that wind around the ancient forests turning a corner the smell of horse and oxen fills the summer air almost shifting the stale taste of hard tack from your throats.

A number of wagons queue along the road as their owners a group of most likely local farmers and merchants gather round arguing loudly and aggressively with a pair of road wardens at a small hut and wooden barricade made of several logs tied together into a cross shape.  

The players may wish to intervene and anyone approaching will over hear that the argument is about an increase in road tax for wagons which is apparently triple the normal cost, some players may suspect that this might be the road wardens attempting to overcharge the farmers but they are only partly right. (The taxes have increased by a large amount though the road wardens have added a few extra silver on top.)

This is an ideal location for the party to buy any last minute items from the merchants and perhaps perform easy Gather Information or Knowledge (Local) checks about the area to see why the price may have increased so drastically. If your unsure for a reason to give to your players then the two simplest are "to fund extra patrols to flush out bandits" or "to repair a section of the causeway."

Anyone threatening violence will find themselves been ridiculed by both the guards and the farmers for their foolishness, while the wagon owners are angry they are not willing to attack the local guards for doing their job. However if the player(s) continue then one of the road warden will ring his hand bell summoning the other 8 currently on break in the guard hut, if this still doesn't deter the players then the farmers and merchants will fee back to their wagons while the fighting commences and I recommend using Simon Newman's Experienced Guardsman for statistics of the ten Road Wardens.
If this combat does occur unfortunately this adventure will be heavily altered for it to continue but my recommendation are:

• If they win then in the panic as the wagon owners (including Samuel ) attempt to flee, one of the bandits disguised as a forester approaches them warning them that another Road Warden patrol is returning shortly and he can guide them into the forest to escape. If they question why he is helping them he lies saying the Road Wardens killed his brother.

• If they lose they are released later that evening from the crude wooden cells behind the hut by the bandit disguised as a forester who gives them the same reasons as above.

However if the party does not resort to violence and return to the wagon Samuel will not wait for long and motioning for the party to follow leads them back around the corner where he reveals an old crossroad marker hidden in the long grass and the remains of a trail.   

Turning the oxen away from the main road and down the overgrown remains of the nearly hidden pathway Samuel pipes up when he sees the curious looks you give him "Don't worry, don't worry there's an old road that passes through here and while it gets a bit overgrown this time of year its perfectly safe. It should lessen the trip by a few days too so soon we will be resting in proper beds."  
However for all of Samuels smiles and reassurances he cannot hide the faint shuffling of unease and nervous glances of the guards accompanying him as the wagon moves into the shade of the canopy.

Inform the party as they travel through forest that the vegetation rather dense and overgrown with the dis-repaired trail slowing progress as the trail occasionally has to cleared for the ox drawn wagon.

If the players wish to make Survival checks allow them to do so, results for decent rolls could be helping the wagon progress faster or manage to collect berries or capture a rabbit or pheasant. While these checks will not have a long term effect it gives the players a feeling of control and interaction within the setting.

Knowledge checks however do give chance to learn more about the area.

Knowledge (Local, History, Geography): The Road/Faham
DC 10 : The road the group now travels down was once one of the many roads that ran through the forest, all of them connecting with the town of Faham. However once the town was destroy approximately 120 years ago they fell into disrepair from lack of use. 

DC 15 : Faham had a mostly human population of 600, and there was partially know for its central market which was built around the statue of a fox which was apparently there before the town itself. It was governed by a council of elders, known as the Synod of Eleven made up of prominent citizens and the founding families. Its destruction is not well documented but it is believed to have been caused by orc invaders.

(Local and History only) DC 20 : The White Ember tribe was the orc tribe responsible for destroying Faham however it is said that that the orcs were provoked by the actions of one of the council who had attempted to break a trade agreement with them by hiring mercenaries to destroy the tribe without consulting the rest of the council. When the council of Faham refused to hand him over to the tribal leaders not believing them the tribe attacked burning the town to the ground but mostly dying in the attack. Today the burnt out ruins are often home to bandits and monsters

Knowledge (Local, Nature): The Forest
DC 10 : This large forest is well know for its game but there are also many tales of monsters and bandits within it.

DC 15 : It is said old magic permeates the forest and dire beasts are common and animals breed much faster than normal in great numbers but this attracts not only hunters from the local villages but goblins, orcs and gnolls hunters and raider bands.

(Nature Only) DC 20 : Due to its magic and size several rare herbs such as Sleepweed grow in great number within the forest and mages and healers often buy dried herb stocks gather from
these woods.

Finally with dusk approaching the party reaches a fork in the trail and an old way stone:

Breaking into a small clearing the trail almost resembles a proper road here with several patches of mossy cobbles visible through the grass. A lone weathered way stone seemingly untouched by the plant life around it points with twin arrows to the north underneath which faded runes give hint of further information, looking northwards you can see the where a road must of once stood by the clear parting of the trees for quite a distance even with the fading light as dusk approaches .

Anyone can attempt to read the way stone but all they can decipher is a pair of symbols pointing down the path forking off the main trail representing two different locations, the first location one days travel away and another at 3 days travel distance. A Decipher Script check at DC 14 will determine these symbols represent a Guard House as the location a days travel away and the second location been Faham.

With the way stone investigated and night approaching the guards recommend this is where the group should camp for the evening:

Gazing up a the darkening sky Samuels two guards discuss amongst themselves in a quiet voice before calling over to you all "Perhaps we should begin making shelter before we lose all light, I doubt we will find better place to camp on the trail." Frowning for a moment Samuel nods in agreement before looking your way to see if you agree. 

Hopefully the party agrees but in either case once the party gives its answer further down the trail a group of five roughly clothed men with green and brown cloaks step from the foliage carrying a dead boar strapped to a stake

Suddenly further down the trail there is a rustle of dried leaves and a quiet sound of cursing a small group of men step from the tree line joining the path all wearing thick cloaks of faded greens or browns lined with fur, a pair of men carrying a stake between them hefting it on their shoulders adjusting the weight as the large slain boar tied to it sways as they walk. Turning to head up the path towards you the men freeze as they see your group the remaining three men instinctively notching their bows though not drawing them as they study you.

Initially wary the two groups exchange pleasantries from a distance (If the players don't attempt to attack, if they do Samuel will attempt to dissuade them) after which the passing "hunters" offer to share their days kill of fresh boar in exchange for a few silver, a keg of cider and some supplies for their camp as well as use of the camp fire for the evening. With the opportunity of a real meal Samuel with the minimum haggling eagerly accepts though he insists any left over meat shall go towards his own supplies.

As the hunters approach beginning to set up their own equipment the leader amongst them a tall thickset man his short cut blonde hair mixed with streaks of white greets you with a nod, though it is difficult to detach your gaze a large trio of scars from some great claw crossing across the left side of his face and neck. Beside him the shortest of the group smiles widely making him resemble a grinning youth as he give you a playful bow "Ah good to see some company, do you have any news of what's happening as of late I would love to hear what's been happening." His fellows roll their eyes as one lightly cuffs the cheerful hunter causing his hat to slip slightly revealing pointed ears.    

The party (been PC's and usually genre savvy) may be wary of the hunters, abilities such as detect evil will detect two (the ones carrying the boar) of the 5 hunters as evil though a player should be reminded that simply because someone pinged as evil this is not just cause to murder them to most people.

Anyone questioning the "hunters" on their knowledge of the local area will find while most of the hunters will give information up to a DC 15 results on the checks above, The two evil "hunters" seem unwilling to talk about the hunts and will instead complain of gnoll gangs in the area grabbing one or two of the other hunter groups to use as slaves. 
 Inquiring about the leaders scars will simply result in been told "They were given to me by the biggest creature I ever hunted and I'll speak no more of it." though several of his group are happy to join in with the party if they attempted to guess what it might be suggesting a troll or a dire bear.
A Knowledge (Nature) or the Heal check of DC : 18 will confirm whatever gave the scars must be at least bear size or larger.

The most talkative of the group is the young half elf who introduces the scarred leader of the group as Lewis (though that is just a pseudonym, his background and real name revealed next article.) and himself as Rewyn explaining to whoever is talking to him that Lewis dislikes talking due to his injury. While Rewyn is happy to speak at great lengths to the party most of it will be about hunting misadventures and tall tales he as heard and anyone listening to his throughout the evening may realise they still know nothing of detail about the hunters. 

The evening continues with a feast of boar flavoured by various herbs provided by the hunters and the hunters opening their small keg of mulled cider as the two groups trade stories and news.
These herbs are a mixture of  sleepweed and normal flavouring and preserving herbs but diced as they are it is not possible to tell them apart.
Allow the party to role fortitude saves but inform them it is for fatigue and alcohol (While all the PC's will fall unconscious this can be a fun way of determines who falls asleep first, anyone rolling a natural 20 however will find themselves beaten unconscious at the end of evening by the remaining hunters/bandits) more alert members of the group may realise they are becoming tired and sleepy far faster than normal but most will assume it is just the combination of the long trek and a proper meal with alcohol. The hunters try their best to keep up with the party but they know that more of their group will arrive and watch from the forest so if they pass out they won't have to worry too much.

When the last of the group finally passes out from the drugged meat the hunters load the unconscious merchant, guards and PC's onto the wagon driving it toward their camp.

FAQ about prologue: 

Isn't this just railroading the players?

While I have to agree unfortunately any adventure that requires a party to be captured usually needs to have some rail roading involved, while I dislike it I try my best to hide it when it is required and sometimes giving the illusion of choice is as important as having a choice.

Wouldn't elves be immune?
No, sleepweed is nonmagical drug and elves are only immune to magical sleep effects.

I have a player playing something immune to poison/doesn't eat?