From publisher blurb:
Level-5 D&D 5e + Shadowdark Adventure
In Echoes of a Stolen Heart, two desperate squires sought a perilous adventure to earn renown and glory; they aspired to be ordained knights soon. Within a shunned dungeon, they defeated a decrepit, undead knight. Its cursed helmet magically compelled one of them to wear it. When the squire succumbed, he became an undead guardian; a fresh replacement for the crumbling combatant that the squires defeated.
The surviving squire fled back to town and told his companion's fiancée what happened. Diane Bluegrass, a fierce huntress, believes there is a way to restore her loved man to health. After selling a few heirlooms, she has enough gold to offer a sizable bounty to passing mercenaries. Diane and the squire hire the characters to accompany them into the fearsome dungeon that many generations before have avoided and shunned.