You might enjoy this book on Amazon, I'm reading it at the moment as a refresher... https://www.amazon.com/Waking-Up-Catholic-Converts-Becoming/dp/0989531902
Waking up Catholic by Chad R. Torgerson
Catholicism All-In-One For Dummies
Why We're Catholic: Our Reasons for Faith, Hope, and Love Trent Horn
The Case for Catholicism: Answers to Classic and Contemporary Protestant Objections Also by Trent Horn
Catholicism: A Journey to the Heart of the Faith Bishop Robert Barron
The Incredible Catholic Mass: An Explanation of the Catholic Mass Martin Von Cochem
Like the previous posters said
Rome Sweet Home: Our Journey to Catholicism Scott and Kathy Hahn
Well, it would depend on what you feel your soul is looking for right now.
You say you're agnostic, there are books for people who want to get a sense of the existence of God, like Jacob's Ladder: Ten Steps to Truth. Peter Kreeft, the author of the book, has a handy section on his website going over various perspectives on the verification of God's existence.
There are books for people who want to get to know Catholic faith a little better before committing, like Waking Up Catholic: A Guide to Catholic Beliefs for Converts, Reverts, and Anyone Becoming Catholic.
There are books for people who want to get to know the Catholic faith more in depth, and have some hurdles to overcome, particularly from the protestant objections, like Rome Sweet Home: Our Journey to Catholicism, from an anti-Catholic Presbyterian minister whose battle against the faith pulled him into it.
There are people who come to the Church by reading on the lives of saints, others by reading on the history of the church and how it built western civilization, and others just by reading the news. It's not just a purely intelectual exercise, this is a spiritual quest and as such you have to give your soul what it yearns for.