Holly Brockbank is the twin sister of Noel Brockbank (Holly and Noel, born on Christmas Day), one of the three main suspects in Career of Evil. Strike and Robin travel to Barrow-in-Furness on their hunt to find Noel, and in the process, they encounter Holly.

Holly is described as looking “harder than most men. She had the same long face and high forehead as Brockbank; her flinty eyes were outlined in thick kohl, her jet-black hair scraped back into a tight, unflattering ponytail.” She has thick arms “covered in tattoos from shoulder to wrist. Multiple gold hoops hung from each ear. A vertical frown line between her eyebrows gave her a look of perpetual bad temper.”

She works at a bakery in Barrow-in-Furness, and it’s at the Crow’s Nest pub where she hangs out every evening that Robin approaches her. In order to collect information on Noel, Robin poses as an attorney named Venetia Hall who is investigating wrongful injury claims on behalf of former military personnel and their families. She promises Holly that she will try to get her a financial payout for her emotional and physical suffering caused by her brother and his problems resulting from his time in the military. Robin gets Holly drunk with pint after pint of beer, and Holly gives Robin the lead that her brother last worked in the town of Market Harborough.