Spoilers incoming,

This issue happens after Batman/Superman issue so Lobo has already met the Superman and he is in Metropolis.
Basically Superman wants him out, but Lobo (with the help of his "Supergirl") manages to explain to Superman that he is tracking assasin who is trying to destroy Earth. Interesting that the assasin is going to use Earth as the bullet to kill another target - some very big alien.
Anyway, Superman agrees to help since he can't risk this whole thing getting out of hand.
They find assasin and stop his plans, but Superman prevents Lobo from killing his target.
Luckily Lobo ordered his supporting cast to rig the assasins spaceship and he explodes while running away.
We also get a flashback where we can see that after last issue's flashback some kinda apocalypse has started and everyone is dying while Lobo is trying to protect the princess.

Average issue, nothing amazing but nothing bad either.