One of Us Is Back (Book 3), Karen M McManus

Life hasn't been easy for the teenagers of Bayview.

First they had to prove they weren't killers. Then outwit a vengeful copycat. Now, it's beginning again.

At first the mysterious billboard seems like a bad joke:Time for a new game, Bayview. . .

But when a student disappears, it's clear this 'game' has deadly consequences - and no-one knows the rules. Simon was right about secrets - they all come out in the end.