Red Hand of Mars: Zombie Attack

It was past midnight when they were awakened by the sound of a gunshot. Salisbury, Sobson and Faustmann grabbed their weapons and made their way from their rooms in the guest hall onto the wall of the inner bailey. They discovered a group of men swarming up the stairs from the outer bailey--not peasants with pitchforks, but tough men with military training. Salisbury traded pistol fire with them, but the enemy advanced unchecked until Faustmann rashly and heroically charged the point man and dealt him a knockout blow. The rest of the enemy squad came up the stairs, pistols and shotguns at the ready. Salisbury, realizing they were outnumbered and outgunned, grabbed Faustmann's collar and retreated to the footbridge which spanned the gap between the bailey wall and the second story of the  keep. Sobson, the mechanic, was already removing the pegs which held the bridge in place. The three men retreated into the keep before a hail of gunfire, and threw the bridge down moments before the attackers reached it. Salisbury held them back with his pistol for a few seconds before his luck finally ran out; a slug tore through his left arm, spinning him to the ground. One of the attackers leapt across from the wall to the keep, but Salisbury's defense had bought enough time for Faustmann to seize a table from the Baron's study; the boxer lunged forward with the table as a ram, and the attacker was shoved out the door to fall sixteen feet to the cobbles below.
Inside the keep, Lady Stella and her maid went to the third floor to see to Margaret Heathmoor, who was still working in her lab. Mr. Sator followed, armed with a swept-hilt saber. Heathmoor continued to compound her healing serum; after a few seconds, Lady Stella dredged up memories of her chemistry classes and began mixing a few of her own concoctions.
Meanwhile, Father Albertus Neihus saw the attackers chase Salisbury and Faustmann into the keep. The padre had brought a hunting rifle with him, in the hopes of  boar or roe buck; now he stepped to the window, shouldered the weapon, and fired on a different type of prey.  One of the attackers stumbled, seriously wounded. As the others looked up to find the source of the fire, the priest saw their faces in the moonlight; two of them were the Thule Society men who had argued with the baron that afternoon! The return fire barely missed--one round even tore his collar--and Albertus hastily retreated from the window.
The attackers, stymied at the crossing to the second floor, found their way to the keep's main door on the ground level. The journalist Rathstein raced inside just ahead of them and bounded up the stairs. At the landing, Rathstein turned and fired at point blank range. The leading Thule man fell--but seconds later he rose again, his undead flesh already collapsing and his skin withering, and attacked.
Faustmann remained on the second floor to defend the baron. Sobson scampered upstairs to bar the door to the lab, while Salisbury, Rathstein and  Neihus fought a desperate gun battle. The Thule todtruppen forced them to retreat to the third floor. Lady Stella unbarred the lab door, intending to use her home made smoke flask. And then Sator acted. One quick lunge with the sword, and he ran Heathmoor through. As the woman fell dying, Sator flung an improvised firebomb at Stella. The mechanic Sobson, unarmed and trapped at the end of the lab, tossed a rope out the window and slid down to the ground to escape. Moments later, Sator followed.
Lady Stella quickly put out the flames on her skirt; with the room filling with smoke, she opened the lab door. Unfortunately, just as she did so, the attackers reached the top of the stairs. Rathstein and Salisbury were unconscious; Neihus still stood but was badly wounded. The Thule man saw Lady Stella and demanded "You are the Englanderin scientist?" Stella, startled, said "Yes" and the man instantly aimed his arc pistol at her and took her hostage.
The Thule Society men withdrew. They had paid a heavy price--of the eight men who attacked, four were dead, another was a zombie, and one was seriously wounded--but they had not lost the arc generator or arc pistol and they succeeded in capturing "the Englishwoman scientist". Little did they realize they had the wrong one! Sator had disappeared into the night. Margaret Heathmoor lay dead and her notes were either burnt or missing, but one last vial of regeneration serum was beside her....