Hornlach is described as tall and painfully thin.
The Blade ItselfEdit
When Mercer' Salem Rews is arrested by the Inquisition for tax evasion and threatens to expose the Guild's treasonous activities, Magister Kault orders Hornlach to ruthlessly clean house. Hornlach hires the Styrian assassin Carpi to murder the men incriminated in Rews' confesssion. However, Carpi himself is arrested during a sting operation involving Salem Rews, and implicates Hornlach.
Hornlach is arrested by Inquisitor Glokta, Frost and Severard while trying to flee Adua on a ship bound for Westport. Under torture, he confessed to hiring Carpi to kill the nine Mercers before the Inquisition could question them. He also admitted that the orders came from the head of the Guild, Magister Kault. When he eventually gives evidence in Open Council, he's been so badly tortured his eyes were wide but apparently taking nothing in.