Silverstream of RiverClan is a slender silver-and-black tabby with bright blue eyes. She is the only daughter of Crookedstar and Willowbreeze. She first appears in Fire and Ice when she saves Graystripe of ThunderClan from drowning in the cold river. When she asks what he's doing in RiverClan territory, he replies that he is drowning. On the way back to ThunderClan, Firestar (then Fireheart) notices that Graystripe is watching his pretty rescuer.
After that incident, Graystripe and Silverstream start to secretly meet up. Soon, she falls for him, even thought Fireheart and Mistyfoot warned her against it. Graystripe doesn't care about whether or not they get discovered, and Fireheart is worried. He tries to convince Silverstream to break up with Graystripe, but she refuses.
When RiverClan and ShadowClan attack WindClan, she leaps at Fireheart without seeing who it is. Graystripe calls out for her to stop and she obeys. Fireheart is about to claw Silverstream when he notices Graystripe looking horrified, so he lets the silver she-cat go. She runs off and Graystripe follows her. Darkstripe sees him following her and reports so to Tigerclaw. Tigerclaw starts to suspect something going on between Silverstream and Graystripe.
In Forest of Secrets, Silverstream tells Graystripe that she is going to have his kits. Graystripe is joyful, but also nervous, as he is starting to realize that this is something they cannot hide.
When Silverstream goes to meet Graystripe at Sunningrocks a moon later, she begins kitting, but something seems wrong. Graystripe tells Fireheart to go fetch Yellowfang. Tigerclaw sees him and asks him what is happening. Fireheart brings Cinderpaw and Tigerclaw. Cinderpaw orders Fireheart and Tigerclaw to lick the kits and warm them up while she helps Silverstream. Cinderpaw saves the two kits, but Silverstream dies from blood loss. She tells Graystripe that she loves him and to take care of her kits. Silverstream is buried near the river.
In The Darkest Hour, she gives Firestar a life for loyalty to what he knows is right. Later, she runs alongside ThunderClan to help them defeat Scourge.