It's not exactly ho-ho-homicide, but there's still something rather merry about Jane Langton's seasonal mystery, "The Shortest Day: Murder at the Revels." Always a witty and literate writer, Langton is in especially fine form here as her series sleuth, professor Homer Kelly, is upstaged by his wife, Mary, when murder makes an entrance at Harvard University's annual Christmas Revels.
The first death, though, that of a popular folk singer set to perform in the festival, appears to be an accident. Only Mary seems to notice that Morgan Bailey is pathologically jealous of his wife, Sarah, who's directing the production. But even Mary is sidetracked at rehearsals by a tent city being erected in Harvard Square by Cambridge's homeless.