So ive been playing through doing the small missions for the thieves guild, after doing a certain amount of these it unlocks the special quest called summerset shadow.

Im only at the second part of the quest were i need to speak to niranye but the marker is leading me way off the map whilst in windhelm (once i leave it tells me to go back in) and shes not at her stall or in her house either :S is there anyway to fix this? or am i just missing something?