Mystery Rider, Horses and Friends Series by Miralee Ferrell and published by David C Cook.
In Mystery Rider, book number 3 in the Horses and Friends series by Miralee Ferrell, Katie isn't sure if she has a problem when snooty Melissa starts boarding her horse at the Ferris family's stable. All of a sudden Melissa is acting nice and helpful, and after all the problems in the past, Katie isn't sure if this is some kind of trick or act. When a hooded rider appears and then disappears riding a beautiful black horse, Katie isn't sure if maybe it's Melissa playing a trick on her. Katie and her friends will need to look to God for a little help in solving this mystery. Recommended for ages 9 to 12 years.