The choice for June is

The Vanishing of Katherine Linden by Helen Grant

The blurb says –  “Pia’s life in the picturesque German town of Bad Munstereifel changes forever the day her grandmother explodes.  The unusual circumstances of her grandmother’s death make Pia the subject of local gossip and she is ostracised by her classmates.  Befriended by another outcast – Stefan, the two begin to investigate the disappearances amongst young girls in the town.  Little do they realise, their detective work will uncover things more horrifying than they ever dared imagine.