If one pre-determined encounter/event (A) [always] takes the characters to another pre-determined encounter/event (B0, then there must be very significant limits on the outcome of (A). Any outcome that would not lead to (B) is precluded.
I took the liberty of inserting a key word - "always" - in there, in order to make this statement true.
But if it's phrased as "... is intended to take ..." instead, then the door is left open for other outcomes and-or unexpected results that might lead to (D) or (F) or somewhere else entirely, even though most of the time it'll probably go (A) to (B) anyway.
There are techniques for establishing what happens next, including framing techniques, that do not depend upon pre-determination and that are not random. They're well-known RPGing techniques these days. In the world of D&D, some 4e D&D books at least gesture towards them.
Even then, however, I know I'd be thinking ahead in terms of (or would want to have prior knowledge of) what comes after "what comes next" if what comes next produces any or several obvious possible results. Example: they're trying to gain uninvited entry to the palace to negotiate with the Duke. Were I DMing this I'd want an idea of the flowchart of likely upcoming events:
They fail to get in but are able to escape - what next
They fail to get in and get arrested - what next
They get in but are unable to find/speak with the Duke - what next
They get in but their negotiations fail - what next
They get in and their negotiations succeed - what next
Yes this means thinking about (or, for adventure writing, writing out) numerous possible paths and ultimately only using one, but that's the point of being prepared: most of the time, unless something really wacko happens, you're not left winging it if they don't follow the script.