The Land Under the Stairs: A Senior Narrative Book Jacket by Kendra Evans (2016)

Addison Parker is very normal girl: quiet, calm, and hates to draw attention to herself. Some would call her boring. One night she discovers a hidden staircase under her bed, and decides to see where it leads. When Addison reaches the bottom of the stairs, she finds the enchanting land of Roseberry, where nothing is out of the ordinary. Upon her arrival, a gopher named Tubsy tells her about a prophecy in which she is to overthrow the evil sorceress the rules the land. Tubsy takes Addison to the cursed and seemingly crazy Philip Briggs. Philip promises to teach Addison about magic and an ancient spell that will defeat the evil witch. While Addison is training with Briggs, the witch shows up with open arms and a flamboyant and flirtatious attitude. She flirts with Briggs and hints at a past they share. Addison begins to question if killing the witch is right. When Addison reaches the witch's palace, she is welcomed by the witch and given a tour. During the tour Addison learns that the witch was supposed to be queen, until Briggs betrayed her. This left her no choice but to take the crown by force, now killing all who stand in her way. Addison decides to kill the witch, and begins to cast the ancient spell. However, when it doesn't work she is left to her own devices. No spell she casts seems to affect the witch, and she is running out of options. Addison then finds a magic mirror and tricks the witch into getting sucked in, sending her to an unknown realm and banishing her from Roseberry forever. Addison is crowned queen for her good deed, and all seems happy again. That is, until the witch decides to come back.