After an otherwise thorough search produced nothing

Except a cut on my foot from a falling painting that was mounted on heavy wood, we resorted to the kitten detector (Felis silvestris catus, of the adult variety), by taking him into the bedroom. He lashed his tail and got up high on the chest of drawers, so we took that as a sign that the kitten was in that room, and took my friend's bed apart as far as sheets, pillows, and mattresses were concerned. The kitten was in one of the two box springs. He is now in the bathroom, and so he shall be while we make sure he has food, water, and until he and the cat are more comfortable with one another.