Mystery of the Crimson Ghost — Phyllis A. Whitney

While spending the summer in the country, a young girl falls in love with the neighbor's horse, but her attempts to befriend the mare are thwarted by mysterious events involving a crimson ghost-dog and the horse's "crazy" owner.

Suddenly Janey awakes! The horrible noise fills the night..screaming, wailing! It's the fiery ghost that haunts the estate where old Mrs. Burley and her beautiful mare, Star, live.

Janey knows that if she ever wants to ride Star, she must solve this chilling mystery!