The Ex-Mrs. Bradford (1936)

Relations between Dr. Bradford - 'Brad' - and ex-wife Paula are surprisingly romantic. They divorced because Brad hated being dragged into murder mysteries, to which mystery writer Paula is addicted. But through horse trainer Mike North, Brad is embroiled in the case of a jockey who died of "heart failure" during a race. As they pursue clues, Paula pursues Brad for remarriage, and assorted hoods pursue the Bradfords.