Simplify the following text for a Grade 19 native English-speaking person.
Original: Booklist 's starred review approved of the novel 's humor action , and plotting : `` The Percy Jackson & the Olympians series is built around a terrific ideaâ '' that the half-mortal offspring of Greek gods live among us , playing out struggles of mythic scaleâ '' and Riordan takes it from strength to strength with this exciting installment , adding even more depth to the characters and story arc while retaining its predecessors ' nonstop laughs and action . ''
Simplified: Booklist 's starred review said , `` The Percy Jackson & the Olympians series is built around a terrific ideaâ '' that the half-mortal offspring of Greek gods live among us , playing out struggles of mythic scaleâ '' and Riordan takes it from strength to strength with this exciting installment , adding even more depth to the characters and story arc while retaining its predecessors ' nonstop laughs and action . ''