A new propulsion test puts the ship in harm's way as Worf deals with his son.
Worf's son Alexander arrives on the Enterprise to live with him, a disruptive change for both. The boy struggles to adapt to life on a starship and has trouble with his father's expectations. Meanwhile, the ship is assisting in the testing of a new kind of propulsion system that uses a soliton wave, which turns out to be dangerous.
The story is a family drama that gives Worf the challenge of being a parent, and it contains a gentle subplot about discipline and love. The science plot adds tension, with a ship in danger and Data and Geordi working to solve the problem. It is a quiet, thoughtful episode that develops one of the series' most important relationships.