Expensive is related to Cost. Cost is related to Involved. Involved is a form of Involve. Involve is a synonym of Overwhelm. 
Book is etymologically related to Bake. Book is related to Hero. 
Expensive <--RelatedTo--> Cost <--RelatedTo--> Involved --FormOf--> Involve <--Synonym--> Overwhelm 
Bake <--EtymologicallyRelatedTo-- Book <--RelatedTo--> Hero 