See this online ebook:
- Commentary on Daniel, by Fr. William G. Most (1997). May be read online on this page, together with a brief introduction to the Book of Daniel, at Catholic Culture.org (Trinity Communications, 2001); and on this page at the EWTN Libraries. [N.B., This is part of the Father William Most Collection, indexed by Phat Catholic Apologetics.]

Daniel in the Lion’s Den. Image from Wikipedia
On the Feast of the Holy Prophet Daniel in the Catholic churches of the Byzantine rite. For other legally free ebooks, you may access the List of Free eBooks (Arranged by Title) and the List of Free eBooks (Grouped by Subject).
“[T]hat day shall not come, except there come a falling away first, and that man of sin be revealed, the son of perdition… Even him, whose coming is after the working of Satan with all power and signs and lying wonders, And with all deceivableness of unrighteousness in them that perish; because they received not the love of the truth, that they might be saved…
“But we are bound to give thanks alway to God for you, brethren beloved of the Lord, because God hath from the beginning chosen you to salvation through sanctification of the Spirit and belief of the truth… Therefore, brethren, stand fast, and hold the traditions which ye have been taught, whether by word, or our epistle.” (II Thessalonians ii, 3, 9-10, 13, 15 KJV)