G&S bought a 42-year-old specialist and made an unfashionable decision: it let the acquired agency keep its name. The result is a two-brand communications group built for businesses whose stories arrive tangled in science, regulation and jargon.

She swapped Capitol Hill for the corner office of marketing, and now she has to make accounting, tax and insurance sound like something worth reading. Here is how a campaign operative became the brand voice of a $2.8 billion firm.