Season 4 of the series picks up where Season 3 ended – with Harry (Alan Tudyk) and his baby Bridget stuck in prison on the Grey Moonbase and a new alien shapeshifter impersonating him back on Earth.

Members of your crew have been replaced by an alien shapeshifter intent on causing confusion, sabotaging the ship, and killing everyone. Root out the ‘Impostor’ or fall victim to its murderous designs ...

Members of your crew have been replaced by an alien shapeshifter intent on causing confusion, sabotaging the ship, and killing everyone. Root out the 'Impostor' or fall victim to its murderous designs ...