Rather than go chapter by chapter, I'll summarize the whole book as space is limited. The Robe is a historical novel by Lloyd C. Douglas, a former minister, set during the time of Christ. The main character is the Roman Marcellus Gallio, who is sent to Minoa as punishment and later wins the robe of Christ after throwing dice for it. This is taken directly from the Biblical story of the crucifixion. He puts the robe in care of his Greek slave, Demetrius. Marcellus is not convinced of Christ's guilt, and at a banquet, other Romans mock him until he tries on the robe, which has an immediate negative effect on him and his mood.

The woman who loves Marcellus, Diana, pleads with the emperor Tiberius to let him come back from his exile. Marcellus's poor mood continues until Demetrius brings the robe to him, which he touches it and he immediately feels better. He is curious to learn more about Christ and his message, which he explores as part of his official duties. Marcellus talks to those who knew Jesus and hears about several miracles that he performed. Eventually, he converts to Christianity, even though, technically, it was not an established religion yet. Tiberius is none too pleased with this development, as the Romans were suspicious of new religions and anything that challenging the status quo. Tiberius forces him to choose between Jesus and Diana. Marcellus chooses Jesus. After Tiberius dies, Caligula comes to power and Diana is to marry him. However, she ends up converting as well and they are both executed. The robe ends up with Simon Peter.

While it was a very popular book, it is probably best remembered because of the film adaptation with Richard Burton in the lead, part of a cycle of films set during the Roman era.