I am writing a book review. I've encountered a problem with my sentence, "The Song of Albion Trilogy are the best books I’ve ever read". Even though I am talking about a trilogy or series, it is not only the best series I've read, but also the best books I've read including stand-alone novels. I want to say this using proper grammar. Should I be using "is" or "are" and can I use "books" or do I have to say it differently? I understand that if I said "trilogy" instead of "books" that I would use "is", but I am wondering the correct verb to use if I keep my original sentence. I can't do "The Song of Albion Trilogy is the best books I’ve ever read.", can I?
Whether a noun or noun phrase in English is grammatically "singular" or "plural" is not equivalent to the question of whether it refers to a single object or multiple objects. For example, the noun phrase "a pile of clothes" probably refers to multiple articles of clothing, but it takes singular verb agreement: "A pile of clothes is sitting on the floor".
"The Song of Albion Trilogy" is a singular noun phrase, and I don't see any basis for saying that it is "actually plural"—not even in the context of a sentence like this.
In the sentence "The Song of Albion Trilogy are/is the best books I’ve ever read", the subject is "The Song of Albion Trilogy". The noun phrase "the best books I’ve ever read" is just the predicative complement.
In general, the grammatical number of the predicative complement does not determine the number of the associated inflected form of "be". Instead, the inflected form of "be" takes the grammatical number of its subject. For example, we can say things like "Water shortages are a problem", where even though "a problem" is singular, the preceding form of "be" is inflected for the third-person plural (are) because the subject of the sentence, "water shortages", is a plural noun phrase. This is covered in the answers to the following question: Agreement in "[Singular Noun] Is/Are [Plural Noun]"?
Based on this rule, "The Song of Albion Trilogy are the best books I’ve ever read" would be considered ungrammatical. It doesn't sound correct to me.
"The Song of Albion Trilogy is the best books I’ve ever read" would be grammatically correct according to the rule of subject-verb agreement, but I agree that it sounds odd. I think Hot Licks is correct to advise rewording the sentence.
In a comment, Edwin Ashworth brought up the concept of "notional agreement". I didn't get into this in the first version of this answer because I didn't think it was relevant; however, there do seem to be some examples of people using plural agreement in sentences where the subject is a noun phrase headed by "Trilogy" and the predicative complement is a a plural noun phrase.
Don't get me wrong, the Thrawn Trilogy are the best Star Wars books, still I don't think they would do so well as movies.
(Drudenfusz, 02.09.2012 , 07:33 PM | #13 comment on thread "What are the best SW books" in STAR WARS: The Old Republic > English > STAR WARS Discussion)
It is pretty much unanimous that the Dark Night Trilogy are the best Batman films to have ever been reached cinemas.
"Batman v Superman director Zack Snyder wanted Christian Bale his movie but not as The Dark Knight", by Jack Shepherd, The Independent
You'll have to use your judgement to decide if sentences like this feel grammatical for you.