Ah that sucks. I'd just ring and say. My son is missing his iPad and so and so can't find it at the house. Can u ask Peter if he saw it before he left maybe we're leaving a spot out that we haven't looked. Or. maybe Peter grabbed it by mistake? My son is upset so we're trying hard to find it.
And if Peter does have it and return it. Watch out from now on. Don't let him over inside to play just play outside. And don't take valuables to sleepovers with him there. Good luck. Never easy confronting. Let us know what happens.