Nimhe, the Poisoned One

Walkthrough
When in Understone Keep, the Dragonborn can speak with the court wizard, Calcelmo. At first, the wizard is very brusque but eventually becomes a bit more talkative. When the Dragonborn asks about his current excavation, the wizard mentions that a Giant Frostbite Spider is making it difficult to explore the Dwemer ruins.

Kill Nimhe inside Nchuand-Zel
The Dragonborn can then offer to take care of the named spider, Nimhe. Enter the ruins and kill the spider.

Tell Calcelmo that Nimhe is dead
Return to Calcelmo with news of the dead spider. He hands over the Dwemer Museum Key as reward.

Nimhe die Vergiftete