In the Tower of the Wizard King - Age of Wizards, #1

In the Age of Wizards, Time is a commodity more valuable than gold. Her magic is dormant. When Aoife (EE-fa) Burke rushes home after the unexpected death of her father, she discovers her mother has vanished amidst inexplicable circumstances. She returns to her childhood home to search for clues of her mother's whereabouts but another shock awaits her. Sean O'Connell, the object of her girlhood crush, has purchased the family home.
She senses Sean is hiding something from her, refuses to let her inside and does everything he can to keep her out. A determined Aoife breaks inside and stumbles upon an antique trunk in the attic. When she opens it, instead of the normal musty clothes and ancient letters, she finds a stairway leading into darkness. It calls to her and she cannot resist stepping into the trunk and onto that first stair where it leads her to magical truths her mother never wanted her to discover. His magic is dangerous. Sean O'Connell has been assigned by the Inter-dimensional Portal Protection Agency to keep Aoife and her mother out of Faery.
But when she breaks into the house and disappears through the portal in the trunk-like her mother-he has no choice but to follow her, even though stepping into Faery will force him to face his past. Keeping her safe and out of the hands of the Wizard King also becomes a fight to save Aoife's life from her own mother, who has discovered a time portal in Faery leading her back in time to alter her past mistakes, putting Aoife's life in peril.
Sean is willing to do anything to make sure she's safe. Even if it means he has to tap into his dangerous magic to do it.