Noah told Emma about what he thought about Audrey, but Emma was quick to declare that Audrey was definitely not the killer, so Noah set out to prove she was. 

He text the motel guy and the guy asked him to meet him. When Noah went to meet him, he was kidnapped by who we thought was the killer, but it turned out to be Audrey trying to find out what he know. 

Noah made it clear that he was into Audrey, but she declined his advances. The real killer appeared on the scene after they heard Emma. Audrey revealed that she wasn't actually tied up and could help. 

Noah was shocked, but let Audrey finish and the two of them joined Emma who was being attacked by the killer. The three of them escaped and ran into Kieran, who says he was watching Emma. 

Kieran then goes to Miguel to let him know that he thinks it could be Emma. 

Noah and Audrey finally confide in one another and Audrey tells Noah that the motel dude is dead and that she brought Piper to town, but did not take part in any killing. 

The police realized the mysterious emails came from Emma's IP.