The army in question could be traveling through the underdark, emerging from caves near their intended targets.

A great enchantment creates a field of invisibility, preventing anyone from outside the field seeing the army within it.

Or perhaps the army marches through a parallel plane, opens portals in the middle of their intended target, and overwhelms them from within.

Let the players each play a character from a nearby town where the PCs made a good impression, preferably characters previously introduced as NPCs. The players can use these inexperienced characters to try and break their real characters out.

This gives you the chance to break up the campaign a bit and run something a bit more about wits and luck. If the rescuers are successful, then the players have succeeded at rescuing their own characters. If the rescuers fail, however, then they too can be captured and now it’s up to the PCs to not only escape, but break out their would-be heroes as well.

Traditional means of fighting the creatures, which have come to be called slivers, have failed utterly, and now the king is starting a new tack. The court’s alchemist, and the king’s closest adviser, Tarangus Blaque, has been tasked with researching the creatures to find out how to get rid of them once and for all.

Having worked with the PCs before, and knowing this job will require reliable people, Tarangus sends for them personally. His first quest is a simple one; they must only capture one of the creatures, preferably one of the smaller ones (a sliver drone).

After the PCs acquire one of them, Tarangus studies it for a while, before deciding he needs a more potent specimen and sends the PCs out once more. On the bright side, Tarangus has concocted a salve which, applied to the crest of the creatures, should incapacitate them.

This time, it seems as though the slivers were expecting the PCs and set a trap for them. When the PCs do manage to acquire one of them, if they tell Tarangus about the trap, he will be quite surprised. He does not believe such creatures are capable of such complicated tactics; there must be a more intelligent mind guiding them.

Eventually, he discovers that the slivers communicate and identify each other with a specialized gland. If the PCs can procure more sliver drones (one for each PC), he believes he can make a “disguise” which would allow them to enter the hive and explore further.

He gives them some more of the sedative he’d created to aid them and accompanies them in their task. This time, the PCs discover that the slivers have adapted and are no longer affected by the sedative, complicating the task once more.

When the PCs capture the requisite slivers, Tarangus creates their “disguises.” Essentially, he takes the gland of each sliver and puts it in a small phial filled with a preserving compound. These phials are hung as pendants from each PCs neck. Finally, he warns them of two things:

1. Even preserved, the glands will not last for more than about an hour.
2. If, as he suspects, a more intelligent creature leads the slivers, it will likely be able to see through the disguises. They should be careful if they discover the leader and avoid being seen by it.

Tarangus gives the PCs a large barrel filled with a special blend of his own explosives. Their final task is to find somewhere within the lair to detonate it which will cause the most damage to the hive, and to determine if indeed there is a leader. If there is, the PCs should not allow the vile thing to escape.

Along the way, the PCs meet up with some German scientists with their own military escort who are bound for the same site. The commander of the US troops decides that it’s in their best interests to work with the Germans, and so the two groups go together to investigate.

When the source of the mysterious radio signals is finally located, it’s discovered to be an alien craft hidden in the heart of a pyramid. The following day, while the scientists are investigating it, the Germans betray the Americans and kill all of the troops. One of the soldiers manages to warn the PCs, but they’re now on their own and must make sure the technology doesn’t fall into German hands, not to mention escape with no military or survival training!

He’s begun bolstering his army, and on top of that has decided to complete and re-man the fort at Weston Hill. It’s been standing derelict for the better part of a century, though, and the first thing the king decided should be done is to assess the current situation. At the moment, his army is occupied with recruitment and restructuring efforts, so the king must hire adventurers to go and explore the fort. Of course, he ends up hiring the PCs.

The situation at the fort is relatively benign. It is somewhat difficult to enter; the portcullises are long-since rusted shut and the stone walls are as impassable as they were designed to be. However, it should be fairly simple for a well-prepared group to gain entrance.

Most of the buildings have been destroyed by time and the elements. The barracks and tower still stand, though. Exploring the barracks, the PCs will eventually come to a wall in the basement which appears hastily-erected. If they examine it, they find it to be hollow and, behind it, is a door.

The door has been barred and locked, the lock melted with acid, spikes of metal have been used to jam the door shut, and mortar was used to seal it. Clearly, some effort was made to ensure that this door should never be opened, from one side or the other.

Inside are several dozen dessicated corpses, the remains of the supposed mutineers. Several of them are missing chunks of flesh, and teeth marks can be seen on the bones. One corpse remains notably intact, and is wearing finer garments than the rest. It was the commander, and in his hands he holds a journal detailing what really happened.

A few weeks after they’d first settled into the fort, one of the soldiers fell ill, complaining that he was seeing and hearing things. Hours later, he turned hostile, savagely attacking the doctor. He was locked in the brig. A few days later, the same fate befell another soldier and another, and within a week all but a few of them were locked away in this room. Finally, when the commander himself started seeing things, he ordered his second-in-command to lock him in with the rest and leave the fort, and to convince the king to abandon it.

If the PCs tell Thornwald what happened, he dismisses it and orders the fort re-staffed. He also hires the PCs on as scouts, to explore the land around the fort. He charges an experienced man by the name of Sir Andromus Galwain to command the fort.

A few weeks after the fort is re-opened, Sir Galwain sends for an audience with the PCs. He explains to them that the same events which happened when the fort was first opened are happening again; he’s sent word to Thornwald, but suspects the king will not allow the fort to be abandoned. Galwain doesn’t want to put his own men into investigating what’s happening, for fear of what the truth of what happened so many years ago might do to morale, and so he asks the PCs to figure out what’s causing this sickness and fix it.

Some teenagers on the train, seeing the American man and thinking he looked like he’d have some valuables on him, mugged the spy and ran off. They escaped with his briefcase and his suitcase. They were unable to open the briefcase, which contained the biological weapon as well as the spy’s collected intelligence, but in the suitcase they found the prototype weapon.

Looking to make a quick buck, they sold all the stuff to a man named Alexei Bobylev. Alexei used the weapon to kill some personal enemies in the Russian mafia. The gun leaves no traces, it’s as if the victim died of a heart attack. The only thing suspect about the deaths is that they all happened so closely together and only two of the dead men were in poor enough health to be at real risk of a heart attack.

And this is where the PCs come in. They’ve been sent in by the American government to recover the spy’s belongings, and keep it quiet. Unfortunately, the string of bizarre deaths made the national media, and now everyone’s swarming over the area. The PCs will have to contend with the following:

The mafia: They strongly suspect Alexei is behind the murders and are looking to exact their revenge.

The Russian government: The PCs have to recover the items before the Russians do; the spy had also gathered some intelligence on Russia itself, and it lead to an international incident if they found out the US was spying on them. Needless to say, the use of force in dealing with the Russian agents is not an option.

The terrorist cell: They recognized the cause of the deaths and immediately guessed that their stolen technology would be found there. They’ve sent men to recover it.

Time: Immediately after committing the murders, Alexei went into hiding. Since then, he’s been trying to bust open the briefcase, and his less-than-gentle means could spell disaster if he breaks the seal on any of the vials inside.

The little girl’s name is Leigh, and shortly after meeting her a crack of thunder announces that the rains have begun. A torrential downpour soaks everyone almost instantly, and Leigh offers to lead the characters back to her house.

As they follow the girl through the forest, they can hear a female voice shouting, “Leigh! Leigh!” It is not long at all before they come to a clearing with a small manor, and standing in the doorway is a teenage half-elven woman, delighted to see her sister appear but concerned when she sees the PCs.

The characters are quickly introduced to the rest of the family. The sister who was shouting for Leigh is named Kacey. Their older brother Barend has just come in from chopping firewood and is placing the axe in a closet when the characters arrive. The father, Crisdean, is a decidedly refined human of about 40 years of age. After some questioning, Crisdean thanks the characters for helping Leigh find her way back and invites them to stay for dinner and wait for the rains to die down.

Kacey prepares a savory dinner for everyone, and they engage in a lively conversation. If asked about his wife, Crisdean explains that she died in a fire several years ago, and Leigh holds up her doll, saying that the ring on the doll was her mother’s. Crisdean and his wife met as hired help to Ancel d’Chevalier, the former owner of the house, and they were left the house when the old man died.

After dinner, everyone retires to the sitting room, where a portrait of an elven woman dominates the wall above the fireplace. Shockingly, the woman in the portrait could be the twin of one of the NPCs! Crisdean explains that the portrait is of his deceased wife.

The hours pass quickly and the rains show no sign of letting up. Finally, Crisdean sends the little ones off to bed and offers to let the characters spend the night, offering them 4 rooms.

The same character which looks like Crisdean’s wife awakens to a thunder clap with the distinct feeling that there’s someone in the room with her. Another bolt of lightning reveals the suspicious to be true, Leigh is standing at the bedside, holding her dolly as always, and apparently watching the character sleep. When Leigh sees the character wake up, she asks, “Will you be my mommy?” If the character tries to leave, she finds the door locked.

Another crack of thunder awakens the other characters, and they each see a different member of the family in their room. Barend holds an axe high above his head, ready to strike, Crisdean wields a fireplace poker, and Kacey is about to try and smother one of the characters with a pillow. Observant characters will notice that the three of them appear as if in a trance.

The family fights tenaciously, but not particularly well. However, in the mean time, Leigh’s doll has become animated and attempts to cast a spell of some sort on the trapped character. Leigh, for her part, simply stands there and does nothing but watch. If the doll is destroyed, the family drops out of the trance and ceases attacking. They have no idea what they were doing and, depending on their situation when they drop out of the trance, may react with anger, curiosity or disbelief.

When the characters leave, after traveling a bit they encounter a merchant wandering down a road. Seeing their distressed state, he asks what happened. If they describe the story, the merchant recalls hearing about a fire at the old Chevalier manor, but that was forty years ago. The elven matron of the family that was living there, a terrible sorcerer, destroyed the house when her dealings with fiends went sour, killing her and her entire family. Sure enough, if the characters return to the site, they find only a long-abandoned, burned-down husk of a manor house.