In the first chapter of The Case for Jesus: The Biblical and Historical Evidence for Christ, author Brant Pitre discusses C. S. Lewis' trilemma and how he realized that there was a fourth possibility when he first started studying the four canonical gospels: that Jesus is either Liar, Lunatic, Lord, or Legend. He writes:
However, as I continued to study the quest for Jesus, it slowly dawned on me that for many people, there was a fourth option: namely that the stories about Jesus in the Gospels in which he claims to be God are "legends." In other words, they are not historically true. Consider, for example, the words of Bart Ehrman. This is how he responds to C. S. Lewis's argument:
Jesus probably never called himself God....This means that he doesn't have to be either a liar, a lunatic, or the Lord. He could be a first-century Palestinian Jew who had a message to proclaim other than his own divinity.
Pitre goes on to cite several verses from the Gospel of John (e.g. John 10:30 and John 14:9) and notes the fact that Jesus was accused by the Jews of blasphemy and was nearly stoned to death, which is an indication that the Jews thought Jesus was claiming to be God. Pitre explains why scholars such as Ehrman do not accept these verses from John as evidence of Jesus' claim of divinity:
On the one hand, most scholars admit that Jesus does claim to be divine in the Gospel of John....On the other hand, as I came to learn, many contemporary scholars, such as Bart Ehrman, do not consider the Gospel of John to be historically true when it depicts Jesus saying these things about himself. One of the most common arguments for this position is that Jesus does not make these kind of divine claims in the three earlier Gospels of Matthew, Mark, and Luke (known as the Synoptic Gospels). According to some scholars, we have three Gospels in which Jesus doesn't claim to be God (Matthew, Mark, and Luke), and only one Gospel in which Jesus does (John). Now, if this were correct -- and as we will see later on in the book, it isn't -- then it would raise some serious doubts about whether Jesus ever actually claimed to be God.
Pitre explains that the purpose of the book is to address this fourth option and provides a brief outline of his argument in the first chapter of the book:
As we will see, there are compelling reasons for concluding that the four Gospels are first-century biographies of Jesus, written within the lifetime of the apostles, and based directly on eyewitness testimony.
.... equally important, the more I studied first-century Judaism, the more I began to see clearly that Jesus did claim to be God—but in a very Jewish way. And he does so in all four first-century Gospels: Matthew, Mark, Luke, and John. But in order to see this clearly, you have to take one very important step. You have to go back and read the Synoptic Gospels from an ancient Jewish perspective. Otherwise, it’s easy to miss what Jesus is really saying about himself. To be sure, Jesus doesn’t go around shouting, “I am God!” But this doesn’t mean that he didn’t claim to be divine. As we will see, Jesus reveals the secret of his identity by using riddles and questions that would have made sense to a first-century Jewish audience. In fact, it was precisely because his audiences understood that Jesus was claiming to be God that some of the Jewish authorities charged him with “blasphemy” and handed him over to the Romans to be crucified. And by the way, in a first-century Jewish context, it wasn’t blasphemy to claim to be the Messiah. But it was blasphemy to claim to be God.
These arguments (e.g. that the Gospels are first-century biographies of Jesus which are based on eyewitness testimony) also attack notions that Jesus didn't exist or that he lived in India.
Pitre explains in his book that it is written for
anyone who has ever had questions about exactly who Jesus of Nazareth claimed to be
and that it is
not written for scholars, though I cite lots of them in the endnotes.
Therefore the book would be a good introduction to the "quadrilemma".