In The Running Grave by Robert Galbraith, private detectives Cormoran Strike and Robin Ellacott investigate the suspicious circumstances surrounding a wealthy client’s son, Will Edensor, who has become entangled with a secretive religious cult, the Universal Humanitarian Church. As Robin infiltrates the church undercover, she faces escalating dangers, while Strike navigates external threats and personal turmoil. Together, they unravel dark secrets and confront moral ambiguities, testing their partnership and personal limits in pursuit of truth.