Carlos and his friends must uncover who's sending death threats to a wealthy eccentric or Carlos' mother may lose her business, and the reader decides which clues they will follow.

Carlos Serrano is now officially an apprentice detective at Las Pistas Detective Agency. He finally earned his mom's trust, but his next case will be his most difficult one yet. Guests at a creepy mountain hotel are complaining of weird disturbances, threatening messages, and hair-raising howls! Carlos, along with his best friend, Eliza, and her wacky little brother, Frank, arrive on the scene to investigate a ghost. What secrets is this haunted hotel...