What to read after Robin: The Lovable Morgan Horse?

Robin, the fourth book in the Morgan Horse series, introduces the character of Karen Greene and her Morgan, the lovable, sweet, and somewhat lazy Robin. Karen is a bit shy, and desperate for friends. When Robin gets a stone bruise and can't be ridden, the inexperienced rider gives in to peer pressure and rides a horse she knows she can't handle. When the horse bolts and Karen is injured, the girl is afraid to ride any horse - including Robin. Her parents decide to move Robin to Gallant Morgans in the hopes that Heather and Blackjack can help Karen overcome her new fears. Meanwhile, when one of the horses from Gallant Morgans is hurt while on a trail ride, the gang is determined to find who is responsible. Karen hopes to help solve the mystery until an unexpected blizzard hits and she is lost in the woods with Robin. Karen will have to depend on the deep bond she has with her Morgan if they are to survive the cold and snow. 

This story also introduces Robin's sidekick, the adorable gray and white pinto Miniature horse Rerun, and Champ, the small Dachshund puppy with a big attitude.