The Omega team of Grayson, Alex, and Natalie are tracking down the Unlucky 13 who died over a hundred years ago while blasting out a subway tunnel. The four banter back and forth with the ease and humor of good friends that is engaging and helps build their characters. Grayson is such a nerd about facts that when Molly is stalling a security guard by asking a question the guard doesn't know, Grayson answers the question because he can't help himself. The plot has some predictable twists and unexpected ones, while the action scenes are tense with zombie limbs or faces getting crushed from the martial art expert fighters. My favorite was Molly and her mom swing dancing moves to defeat two zombies.
I'm not a fan of flashbacks or cliff hangers. I thought here the flashbacks slowed the pacing down. There are three chapters that are 10 pages each giving the backstory on the Unlucky 13. I didn't think it worked. I don't know if it would have been better to make the chapters smaller or if there was enough to make a separate point of view that had its own mystery going. Or maybe it was competing with the main strong storyline and I just couldn't rouse enough interest in Milton's adventures. Fortunately, there are only three chapters as such that interrupt the flow of the story.
The ending is a cliff hanger and the loose ends are not tied up. I wasn't surprised by the twist because the Frankenstein scene in the hidden bunker made it a bit too obvious. I did like that two new characters are explored more in this book giving the sequel some freshness. While I really liked the first book, sometimes I get bored with second books because it seems a bit of a rehash and I'm too familiar with the characters. New characters help move the plot forward and add novelty.
Molly's character arc in the first book has her dealing with grief and loyalty issues. This book she is still dealing with learning to trust her teammates and work as a team, but she is no longer grieving the death of her mom. Instead her family is bonding, moving forward, and having quality time together. Molly is also trying to face her fear of heights and fear of scary movies. The author has her insisting that she flinches when she screams. While she is tough she also has some vulnerabilities that make her character well-rounded and interesting.