In the light of their betrayal, Kate and Sebastian realize the latest secret they've uncovered must be shared with Jack-a series of letters confirming that his and Sebastian's birth mother is alive. They rush to the airport to find him before he boards his plane. But despite Jack being validated in what he believed to be true all along, he turns his back on his brother and tells Kate that he doesn't understand how he can love her, yet hate her at the same time. Back in Long Beach, Kate and Sebastian discover that Jack didn't leave on his flight and is on a hunt to find his birth mom, Alissa. With summer break arriving, they set off to find the twins' biological mom whom they never knew-and what they discover is unexpected. Their mom isn't alone; a young girl who they suspect to be their half-sister is living with her, hidden away in a remote town. Soon they discover yet another series of lies that Jonathan has left behind. Not only will the truth expose many surprises for them, but the un-expecting will also be affected in unimaginable ways. With every revelation uncovered, a new secret is exposed-and with every exposure a string of lies are unravelled, all with far reaching consequences.