In 2013, journalist Suzanne Rico gets the call. Her mother, Gabriele, is dying. As time ticks down, Gabriele reveals she has written an incomplete memoir about her traumatic childhood in World War II Germany - and makes a daunting last request: "Finish what I started." When Suzanne and her sister, Stephanie, dive into their mother's turbulent past, they come face to face with the mind blowing mysteries that swirl around inventor Robert Lusser - their grandfather - and his work building a secret super weapon for Adolf Hitler. The most puzzling of which is the mysterious, violent death of his wife. As they struggle to bring closure to something as intimate as a memoir, they have no idea of the revelations in store, or the reckoning they will require.