Last week on the Tuesday game...
As the party travelled back to the astral portal that would lead them back to Drandeur, Serrano remembered that his last meeting with Ailen had yielded something useful: namely, some magical means of communicating with a scholar by the name of Dimplebottom. In exchange for promising to never sing again as the Masked Singer, Ailen gave Serrano a namecard and told him that all he has to do is tear the namecard.
Now, faced with the prospect of encountering angry pirates in the Astral Plane or possibly summoning extraplanar help, Serrano decided to try the latter and tore the namecard. This lead them to Dimplebottom's magical travelling shop, where a lifetime's worth of curiosities and wonders could be found. After some business was concluded - where, in exchange for owing the shop 400gp, Serrano purchased a cursed cutlass whose blade proudly proclaims it to be the "property of the Dread Pirate" - the party got down to brass tacks and started trying to find out what Dimplebottom knew about Blackwall.
The gnomish proprietor, as it turned out, knew quite a lot about that particular fiend, but he was not about to give out information for free. As it turned out, he had a job that needed doing: if the party was willing to help his apprentice Bernard the Nose chase a silver dragon out of Wethorp's Royal Court by the end of Late Winter, he would tell them everything he knew about Blackwall. The party agreed, and Dimplebottom dropped them off in Drandeur's Undercity, where they were free to regroup before heading up Cliffside into Drandeur Castle.
After dropping off the duskstone shipment with Excellence, the party decided to use some of their hard-earned wealth to buy fine clothes for Craghammer, Fenrir, and Alistair. The three of them would pose as healers seeking admittance to court, while Serrano and Lia would remain in their armour and pretend to be their bodyguards. To their own great surprise, the ruse worked, and they found themselves in the presence of the Crown Princess Abigail and her loyal knight-commander, Sir Boderick.
The party was allowed to examine the King, but on the strict condition that both Sir Boderick and the court wizard be present at all times. They agreed, and when Craghammer examined the body, he found that while he appeared to be in poor physical health, most of it came from him being bedridden for so long: there was otherwise nothing wrong with King Wethorp.
Thinking that the problem might be in his mind, Alistair decided to Detect Thoughts and, under the protection of Fenrir's Protection From Good and Evil spell, delved deep into the King's mind... whereupon he discovered that the King was currently being possessed by a dark spirit that taunted Alistair's inability to drive him off. Unable to so much as interact with the spirit, Alistair decided to pull out of the King's mind and try something else.
While Alistair was inside the King's mind, Serrano noticed that the court wizard's eyes turned a strange tawny gold, almost as if he was working some sort of magic or invoking some sort of pact. This immediately roused the party's suspicions, but given how their current attempts at curing the King was stymied, they decided to head out of the castle to do some research about possession and exorcism.
Alistair's and Craghammer's research (in the Hidden Schools' libraries and the local Temple of Krubivax, respectively) led both of them to the same conclusion: in order for a spirit to possess another, the summoner must first anchor it to an object in this world - ideally an object that the victim uses often or keeps near him - before the fiend can do anything. Should this anchor be found and destroyed, the spirit will immediately be sent back to its planar home, thus effectively driving it from the victim's mind and soul.
As the party questioned the staff in the castle, they quickly realised that the anchor was most probably a gift he received from Yaniel, a gem-encrusted ivory cigar box that the King kept by his side at all times. When they returned to the King's room to look for the box, they discovered that the box was gone from its usual position on the bedside table: somebody was onto them, and that person moved it to prevent them from destroying it.
Alistair decided to dive back into the King's mind, but this time without Fenrir's Protection from Good and Evil. This, as it turned out, was not the party's brightest idea, for this allowed the spirit to jump from the King's body into Alistair's. Twisting his mind and intentions, the spirit used Alistair's magic to peer into the minds of his fellow team mates, whereupon it discovered that Craghammer was not only an initiate into Krubivax's mysteries, but was also intensely suspicious of Alistair's sudden change in demeanour.
Realising that it would not be able to stay undetected within Alistair, the fiend departed from him and returned to warn its master about the new threat. Now fully back in control of his faculties, Alistair wove another spell to pinpoint the location of the ivory box and discovered that it was located in no other than the court wizard's tower! This confirmed the party's suspicions about the court wizard, and they made haste to confront the dastardly creature who was responsible for the king's long illness.
The court wizard, however, was well-prepared for this eventuality. When the party burst into his chambers, he immediately released four gibbering mouthers whose insane mutterings started driving the party insane. The fight was long and bloody, with party members turning on one another as the madness spread through their ranks like wildfire, but just before Serrano was able to deliver the death blow, the wizard leaped from his tower and - with a parting shout of "this is not the last you have seen of me!" - disappeared into a portal that lead to the Far Realms.