A review by frakalot
Root of Unity by S.L. Huang

adventurous funny informative mysterious fast-paced
  • Plot- or character-driven? A mix
  • Strong character development? Yes
  • Loveable characters? Yes
  • Diverse cast of characters? Yes
  • Flaws of characters a main focus? Yes

5.0

The Root of Unity offers an improvement at every level of the storytelling. The Cas Russell series has been a fun idea applied to a zany set of adventures but now there's a mysterious thread about Russell's past lurking in the plot, the mathematics has become a much more relevant feature, and the character development has gone from being a light-hearted comedic approach to a substantial element of the delivery.

The team is back but don't expect to see Rio, who is again only referenced in this story. It seems likely that Rio will eventually return but so far there's no real evidence of that. My suspicion is that Rio is linked to Russell's hidden past. There's a Rick and Morty style message in a bottle from past Cas to future Cas which simultaneously advances and obscures the mystery, I loved it.

The rest of the gang are working to prevent the collapse of the modern global economy while continuing to bewilder Cas with their genuine gestures of friendship. Thankfully Russell's no kill streak has been broken and the explosive action has returned with an undefined limit.

I've enjoyed the series and this one is probably the best so far. 

It's a little frustrating to figure out what's up with the series having been retitled and reordered and partly rewritten when it got picked up by Tor publishing. From what I read on the author's website, self published book four is the Tor published book two, and Tor book three is the intended but unpublished original book five. My plan is to finish out the original self published four and then jump straight into Tor book three, of course this means I'll miss any new developments in the republished books but I'm not prepared to reread at this point.