The setup of the series, brought forth in the first episode and developed through most of the second, is that Gabriel is looking for his wife Amelia, who never came back from a mission years ago. He's convinced she's not only alive, but still working for the good guys, i.e., our side. In another television age, such a scenario might have continued for more than one season, with the viewers being doled out just an episode or two per year that slowly moved the story forward.
In the case of Intelligence, the scenario didn't survive the second episode. By the time Monday night's hour was over, Gabriel is reunited with Amelia, who is moments later apparently killed (I say "apparently" because unless you see the head literally blown off, you never know in television drama). She's also revealed as working with the terrorists, but then, in a final twist, Lilian discovers that she was trying to help our side - or maybe just wanted to see Gabriel one more time - and Lillian will apparently keep this information from Gabriel, presumably because she doesn't want him distracted.
This is a lot of television plot development for one episode, and Intelligence does it well. Not only is it fun to see Josh Holloway (Gabriel) and Zuleikha Robinson (Amelia) back on the screen together after Lost, but the scene with Gabriel, Amelia, and Riley in the hospital room, with Riley taking decisive action, was an outstanding little piece of stunning television in itself.
Intelligence, like the new television of Almost Human and Person of Interest, brings us into its world with a preface explaining what the series is about at the beginning of each episode. But if the lightning speed of the Amelia arc is any indication, Intelligence may be in a class of its own.
See also Intelligence Debuts