Visitors, Vanishings and Va-va-va Voom by Karen McCombie
There's always something going on in Ally's World! Ally and her mates are tres chuffed when a bunch of delicieuse French boys turn up at school on an exchange. Only Jen seems a bit distracted, but Ally doesn't have time to get to the bottom of it before it's too late - Jen's pulled a vanishing act, and somehow Ally doesn't think she's eloped to Calais.