Death ex machina - Gary Corby

It's the time of the Great Dionysia, the largest arts festival of the ancient world, held each year in honor of Dionysos, the god of wine. But there's a problem: A ghost is haunting Athens's grand theatre. Nicolaos and his clever partner in sleuthing (and now in matrimony), the priestess Diotima, are hired to rid the theatre of the ghost so that the festival can begin. With the help of Theokritos, the High Priest of Dionysos, they exorcise the ghost publicly, while secretly suspecting that a human saboteur is the actual culprit.