Excuse is related to Explanation. Key is a type of Explanation. 
Innocent is a type of Person. Person does not want (to) Hide. Hide is the opposite of Public. Public is related to Road. 
Excuse <--RelatedTo--> Explanation <--IsA-- Key 
Innocent --IsA--> Person --NotDesires--> Hide <--Antonym--> Public <--RelatedTo--> Road 