Thomas Mercier was a Havenite citizen and an officer of the Office of State Security. He was a friend of Captain Avery Vaccares of the People's Navy. Holding the rank of Colonel in 1912 PD, he served as an interrogator at StateSec headquarters in Nouveau Paris. On orders from Secretary of State Security Oscar Saint-Just, he took the enigmatic arms dealer known as Charles aboard the captured Manticoran heavy cruiser HMS Ellipsis to implement a plan to fool the Anderman Empire into a war with the Star Kingdom of Manticore.