Bently, an artistic frog, and Kack Kack, a recently widowed duck, are close friends: she takes care of his laundry and admires his drawings; he agrees to watch over her egg when she wants to visit her sister's new ducklings. Feeling lonely (the egg ``looked so blank''), Bently whiles away the time by painting it—a lucky thing, it turns out, since the decorations divert a passing boy from smashing it. But not from eggnapping. Bently follows, and a picaresque series of adventures ensues, happily concluded when he gets the egg safely home just in time for it to hatch and be named in his honor. Joyce's whimsical, sophisticated narrative includes some unabashed contrivances, especially a balloon that just happens to turn up to transport Bently and his fragile charge. Of most interest are the lucidly composed illustrations, in the tender hues of swampland in a morning mist; Bently is slim and elegant, the duck motherly and rotund, with a rather vacant look. This will never take the place of Dr. Seuss's Horton, but Bently's discovery that watching over the egg makes him care about it provides an interesting contrast to the elephant's more single- minded loyalty. (Picture book. 5-8)