The picnic table was empty still, except for a few crumbs from the previous diners. A trail of ants crawled over the splintered boards in to reach the bits of old bun. Theo watched them, beer in hand, as he waited for his father-in-law to finish grilling the food.

It was the first warm, sunny day of the year and Theo was joining his wife's family for barbecue. The smell of charring meat on the grill was enticing. The food almost done.

His wife, Sarah, played croquet on the lawn with her older brother and his wife and son.

—Food's...