Ikey Solomon is a healer in London in the mid-19th century. He works with his wife Hannah and his mistress Mary Abacus, who is so called because she is good with an abacus. If they run into the lamp, they are sent to the penal colony of Van Diemensland, present-day Tasmania. There, Mary tries to become a successful businesswoman, thanks to her math skills and despite the opposition of her rival Hannah.