On this episode of Person of Interest…

Reese becomes a training instructor at the police academy. He discovers that an internal affairs member has gone undercover to root out a mole.

That mole happens to be working for the Brotherhood, which is preparing to face off against Elias.

The POI team realize that Mini is really the leader, Dominic.

Samaritan has sent out an assassin to find out who foiled the plans to get the virus.

The assassin finally comes face to face with Shaw.