You don’t imagine many laughs in a story about enslavement legacies and erased Black histories. But comedy infuses Winsome Pinnock’s ebullient drama about two Black academics who are given the job of authenticating a cache of 18th-century diaries written by an enslaver. Fen (short for Fenella, played by Sylvestra Le Touzel), is a direct descendant of Henry Harford, now managing his illustrious country estate, and it is she who finds the diaries that catalogued life on his Jamaican farm run by enslaved people. She gives Abi (Rakie Ayola) and Marva (Cherrelle Skeete) full rein of the diaries, so that they can authenticate them for posterity. Harford showed every sign of having been an abolitionist, she says in mitigation, although Abi and Marva’s investigations turn up disturbing evidence of his brutality in Jamaica. Those two women have a tutor-pupil relationship that seems like a twist on Holmes and Watson, and through whom Pinnock deftly captures the intersections of class and race: Abi is from a privileged, Oxford-educated background, of Nigerian descent, whose family history has its …