From what I remember:
It starts off with a US national guard captain calling her team to hop in a shuttle for a quick flight to the moon to stop a team of Chinese and European scientists from poking around an abandoned moon base the Americans left there in a sudden, until explained in the story, hurry.
We found out that the US had been sabotaging moon shot attempts and had blocked itself off from the rest of the world. The scientists find and enter a portal and the Americans chase them.
It turns out that when a civilization gets to a certain advanced technology level then something comes along and wrecks everything, even the garbage collection process. Hence the American desire to leave the portal alone. A chase ensures and a mystery is learned.