Wolfblood - Season 1 Episode 7 -

When Maddy cuts her hand Shannon analyzes the blood on her bandage to prove her friend is a werewolf, though the test is inconclusive. However there is no moon and the wolfbloods have temporarily lost their power, causing Rhydian to faint in class. He is taken to hospital where Tom's doctor mother takes blood samples from him and Maddy which they are desperate to retrieve. Because they have lost their wolfblood powers though the blood tests as human and Shannon believes that all her suppositions about her friend have been false, leading to reconciliation.