Morgan reviews “Mouth to Mouth,” a suspenseful new novel by Antoine Wilson about told almost entirely through one conversation. When the narrator (a nameless struggling author) runs into an old acquaintance from UCLA (successful art dealer Jeff Cook) at the airport, Jeff confesses to saving a drowning man’s life. When he learns the man’s identity, renowned gallery owner Francis Arsenault, he becomes obsessed with determining if he is a “good person” worthy of being saved.