For generations, Ireland has been deeply marked by emigration. By living in one small town in central Ireland - Roscrea, County Tipperary - Joan Mathieu hoped to discover why people continue to leave, and to examine the effect of their departure on those who remain behind. Mathieu's grandmother Sarah left Roscrea for New York City in 1912 at the height of Irish emigration. Zulu is thus both a personal exploration and a more general portrait of a community defined by absences.

From her superstitious old relatives to her young housemates who work at the local ribbon factory, from rebellious Catholic schoolteachers to more or less settled Travelers, Mathieu gives a vivid sense of life in this town of four thousand people and forty pubs.

Mathieu also talks to modern Irish immigrants in New York and discovers that the whole process of emigration has changed because it no longer means leaving for good. These new Irish will not establish roots in their new world, and, surprisingly, they meet with a good deal of antagonism from the established Irish-American community.