Planted deeply in the dark, musical fantastic heart of American storytelling, Cotman’s half dozen tales are ripe for the picking. Dance on Saturday is a collection of stories about transformation, loss, and human nature. Church-going immortals tend life-extending fruit. Swarms of deadly wasps engineered by a polymath sorcerer battle killer snails. Geese take human form and must survive juvenile detention. A high school, high-stakes volleyball game turns demonic. Heroes and monsters people these exuberant, magical tales.