Code is related to Safe. Safe is related to Small. Small is related to Fare. 
Stop is related to Drain. you are likely to find Hair in/at/on Drain. Hair is related to Gray. Gray is related to Stone. 
Code <--RelatedTo--> Safe <--RelatedTo--> Small <--RelatedTo--> Fare 
Stop <--RelatedTo--> Drain <--AtLocation-- Hair <--RelatedTo--> Gray <--RelatedTo--> Stone 