If you're an alien on Earth, you have one giant secret to keep. After a while, even friends want to tell your secret. Kell and Bree plan a birthday party with giants - Big Foot, Cyclops, Goliath and the Jolly Green Giant - while they struggle with keeping their own giant secret. But they have an even bigger problem: Principal Lynx and the Society of Alien Chasers is back with a dog trained to sniff out an alien in a crowd. When Mom is stung by a bee, Kell must find a doctor who can keep a giant secret, too. Will Aliens, Inc. be able to pull off the Giant Party and keep everyone happy?