WHY DIDN'T THEY ASK EVANS ? PB - AGATHA CHRISTIE

"When a man plunges down a cliff, two adventurous young friends decide to find his killer... While playing an erratic round of golf, Bobby Jones slices his ball over the edge of a cliff. His ball is lost, but on the rocks below he finds the crumpled body of a dying man. With his final breath the man opens his eyes and says, 'Why didn't they ask Evans?' Haunted by these words, Bobby and his vivacious companion, Frankie, set out to solve a mystery that will bring them into mortal danger..."