Dark River is the second book of the third or Power of Three series.
- The three children of Squirrelflight and Brambleclaw, also grandchildren of the great leader Firestar, have thrived in their apprenticeships: Lionpaw's strength and energy serve him well as a warrior in training, Hollypaw hones her understanding of The Warrior Code, and Jaypaw explores his mysterious powers and connection to StarClan as a medicine cat apprentice.
- With more experience comes both power and danger: Lionpaw makes a friend – and a discovery – that must be kept hidden; Jaypaw learns a secret that could benefit ThunderClan by damaging others; and Hollypaw knows something that could avert a battle, if she could convince the rest of her Clan.
- The three are torn apart as each discovers darkness: in themselves, in the Clans, and in the past. And, as conflict begins over what it means to be a warrior, rising tensions threaten to overflow, washing away the peace that has existed for many moons.
- Dark River was released on December 26, 2007.
- It was written by author Kate Cary.
- The dedication reads "For Geof"
- The cat in the circle on the cover is Heatherpaw. The main cover is the river located in the hidden tunnels.