Holmes and Watson find themselves on the hunt for a serial killer after a murder rocks their inner circle. Holmes’ neurological recovery regresses and his sobriety wavers as his commitment to catching the killer grows into an obsession.
Supergirl learns the true depth of Serena’s nefarious plans for Earth. Supergirl, Mon-El and Alura must devise a plan to stop her before Serena gets to Earth. J’onn prepares to say goodbye to his father.