Sojourner Nadine Jane Johnson, also known as Mosquito, is an African-American truck driver. Set in a south Texas border town, Mosquito is the story of her accidental and yet growing involvement in "the new underground railroad," a sanctuary movement for Mexican immigrants.

Mosquito's journey begins when she discovers Maria, a stowaway who nearly gives birth in the back of the truck; Maria will eventually name her baby Journal, a misspelled tribute to her unwitting benefactor Sojourner. Along the road, Mosquito introduces us to Delgadina, a Chicana bartender who fries cactus, writes haunting stories, and studies to become a detective - one of the most original and appealing characters in all of Jones's fiction.

We also meet Monkey Bread, a childhood pal who is, improbably, assistant to a blonde star in Hollywood, where Mosquito pays her a memorable visit. As her understanding of the immigrants' need to forge new lives and identities deepens, so too does Mosquito's romance with Ray, a gentle revolutionary, philosopher, and, perhaps, a priest.