The Great Wave by Francis Turnly

As the mother can't shake the feeling that her daughter is still alive, the family tragedy takes on a whole new dimension: on a global, political scale.

If you fancy trying something new with your students, then this is an excellent choice.  With opportunities for multi-role acting, interesting design choices, realistic duologue, the use of subtext and detailed stage directions (not to mention excellently written character dynamics), this would provide some wonderful opportunities for your GCSE students.