Tom Hartigan

In the novel The A.B.C. Murders, Tom Hartigan is the boyfriend of Lily Marbury, the daughter of Mrs Marbury, the landlady of Alexander Bonaparte Cust. Tom met Cust at Euston Station. There Cust had dropped his ticket. Tom picked it up and discovered the Cust is going to Doncaster. This contradicted what Cust had told Mrs Marbury, that he planned to go to Cheltenham.