Captain Kirk and his senior staff have been watching the last log of Captain Ryan of the USS Lafayette. Ryan and his landing party were killed by Berthold radiation emitted by Andronicus' star. Psychiatrist Carl Wentworth has founded a private clinic on Andronicus protected by a dome of transparent neutronium shielding. However, radiation is leaking into the dome, and the Enterprise is headed to Andronicus to evacuate Wentworth and his patients.