Who is the legendary hermit in the forest between the two Canadian towns in Christopher Paul Curtis’s new novel? Thirteen-year-old Benji Alston of Buxton knows him as the Madman of Piney Woods. In Chatham, Alvin “Red” Stockard, also 13, refers to him as the Lion Man for his mane of matted hair. It’s 1901, and 40 years have passed since the events of “Elijah of Buxton,” Curtis’s Newbery Honor book set in a settlement of runaway slaves. The characters from that book are now grown, but they play peripheral roles in this lively, funny and powerful companion novel. In alternating chapters, Benji and Red tell of their budding friendship and brief encounters with the hermit, a gentle, dark-skinned man burdened by a terrible secret. Benji’s tale brims with boyish wit and braggadocio as he battles his younger siblings and apprentices with the exacting editor of the local newspaper. Red, who likes science and suffers at the hand of his racist grandmother, has a quieter, more measured voice. Through the story of Red, the hermit and Red’s grandmother, Curtis explores how we respond to loss and fear. As with his previous books — “Bud, Not Buddy” and “The Watsons Go to Birmingham — 1963” — Curtis’s genial characters and insightful observations of childhood make serious themes accessible to a wide audience.