For their honeymoon Rollo Lenox Smeaton Aubrey, Earl of Redgrave, and his bride, Lilla Zaidie, leave the earth on a visit to the moon and the principal planets, their sole companion being Andrew Murgatroyd, an old engineer who had superintended the building of the Astronef, in which the journey is made. By means of the "R.Force," or Anti-Gravitational Force, of the secret of which Lord Redgrave is the sole possessor, they are able to navigate with precision and safety the limitless ocean of space. Their adventures on the moon and on Mars have been described in the first two stories of the series.