Shadowrise by J.J. Green

After surviving an attack by hostile aliens called Shadows, Jas Harrington and the crew of the Galatheahave made it back to Earth. There, the lies of the ship's acting captain mean that Jas faces some hard questions from the committee investigating the attack.
But more urgent problems become apparent. Things on Earth have changed since Jas went away. Strange disappearances and odd behavior lead her to the question: have Shadows invaded her home planet?
When the Galathea's former navigator Sayen Lee investigates, she's taken hostage. Jas must fight to free her friend from her captors and find out what's been happening on Earth.
If her suspicions are correct, all humanity is at risk.
Shadowrise is book four in the fast-paced, action-packed Shadows of the Void space opera serial.