Through the Portal - The Sentinel Archives, #1

Fans of fantastical tales such as the Fablehaven series and The Spiderwick Chronicles will enjoy exploring the Sentinel Archives. Start off... if you dare... by entering Through the Portal and into the Realm: A land of enchantment and adventure. At thirteen, one passes from childhood into teen-hood. For Malakai Ian LeCrue, turning thirteen also means coming into an inheritance he wants no part of. But someone has to take up the mantel of Sentinel, passed down from generation to generation through Kai's family.
He hopes this tell-tale mark will simply pass him on by. He has none of the qualifications needed to become part of the secret Sentinel Society. Not like his little ten-year-old sister, Wyndee, who is a regular scholar of Weirdology. Even Pops, their grandfather, seems sure the Sentinel Mark will go to the younger female sibling in this generation. Until Pops is brutally attacked and Kai is thrust into a world kept hidden from him by his father who disappeared over a year ago somewhere in the wilderness. Now the only way to help save Pops and Kai's family is to enter this mysterious world through a portal only he can open.
But he's neither been trained, nor is he under the Sentinel protection when he enters the Realm. If he survives, he may not only save Pops, but reveal the staggering truth behind why he'd been kept in the dark about his heritage, and the Realm, in the first place.