Luca Ricci is one of the sons of Niccolo “Mucky” Ricci, a professional gangster and suspect in the disappearance of Margot Bamborough. Strike is able to learn a bit about Luca Ricci when he meets up with Shanker at Shakespeare’s Head. Shanker explains that he’s done some business with Luca and warns Strike well away from the Ricci family, explaining how dangerous they are.¹ 

“‘He’s got sons,’ said Strike. ‘Sons Shanker’s scared of.’

‘Oh,’ said Robin, who fully appreciated the implication.” ² 

Luca Ricci is described as a “very tall man whose face was pitted with acne scars and whose knobbly bald head looked, as Barclay had said, as though something heavy had been dropped on it.” He also speaks in a soft, high voice with a noticeable lisp.³ 

^{1: Troubled Blood, Chapter 27
2: Troubled Blood, Chapter 32
3: Troubled Blood, Chapter 61}