The Colquhouns in Canada

An excerpt of the novel: In Scotland, in 1645, Lady Lilias must deal with the unfaithfulness of her husband, Sir John Colquhoun:
"And indeed Katherine and John were not only causing a lot of pain for her and the rest of his family, but risking the entire reputation of the Clan with his gallavanting. For in those days the notion of infidelity was not only frowned on, but a family as prominent in social circles as the Colquhouns risked losing their status and possibly their lands and titles."
"But she could hardly fault her sister. Had not Katherine, younger and prettier than she, been drawn in by the Black Magic practised by Sir John, the same necromancy which had led to her own downfall ?"