Trouble in Nevermind

From publisher blurb: A mysterious tower randomly appears on the outskirts of Nevermind, an isolated rural village. Sometimes its appearance is fleeting; lasting only an hour or two, at other times it lingers for up to a week or longer. All manner of strangeness occurs when the tower appears: livestock, and sometimes villagers, go missing and weird creatures are spotted in its vicinity. Adventurers and soldiers have been sent to investigate the tower but none that have entered ever return. Now it is the turn of the characters' intrepid party. What will they find in the tower? What power controls it? What trouble does it have in store for them and Nevermind? This is a challenging Classic Fantasy module designed for Ranks 3-4, and a very competent party of 4-6 adventurers, with a decent mix of brains, brawn and magical capability.