The cover art for the 1976 paperback edition of Madeleine L'Engle's classic sci-fi/fantasy novel "A Wrinkle in Time" — featuring a rainbow-winged centaur and a green, glowering, red-eyed face — is iconic. And yet, for nearly 50 years, no one has known who illustrated it. Well, not NO ONE. Not anymore... Endless Thread cracks the case!