It was a friday night in the summer in 2001, Aria, Alison, and Spencer where having a party at the lake house. It was Alison’s 18th birthday and her friends wanted to throw her a party. Earlier that day The girls went to go buy balloons , applesauce and the cake. Later on all the guest come over for Alison's birthday and are all outside. Alison’s friends go and find Alison but they cant find her anywhere. All the guest are looking for her but no one can find her. Aria and Spencer grab flashlights and go out in the woods to see if she was wandering around. They look to see if she might be swimming in the lake but all they saw were white swans swimming in the water. It starts to get really cold so they go back to get their jackets and continue to find Alison. They all hear a scream and water splashing and hurry to the lake. There they see Alison dead in the water floating. They take her out of the water and soon figure out someone murdered Alison buy hitting her in the back of the head with a rock...
The sirens are whaling coming to the lake house. Aria and spencer are such in shock because of what happened. They made sure that no one was missing from the party while Alison was gone. Aria sees one person who she knows she didn't invite. Jenna Marshal was her name. Jenna always had something against Alison. Aria was pretty sure Jenna killed alison after what had happened between them.  Alison made jenna's mother blind by putting a firework in the house. They later find out that Jenna arrived after they found they body. They are desperate to find the killer.