With Don at the Mercy of the group of criminals, it's up to Rod to convince Brighton's CID that something's wrong, and to find him.
It's a solid conclusion to the story, it has definite plus points, but I think it relies heavily on the charisma and huge personality of Billy Murray. It gives a small insight into the two series that would follow in years to come. I imagine it'll be some time before the budget stretched to location work again.
The story was a little limited, but the location work was fantastic, and the acting of course was top notch. Some nice touches of humour at the end.
Good episode, 6/10.