The GM is supposed to railroad the players in the GM turn. Potentially even to the point of saying, “Here are your two options for this; pick one.” Or even, “You’ve been caught by the weather. Everyone Roll Survival Ob4 or get sick!”
The “open secret” of mouse guard is that, if the GM’s planned events resolve the mission, the only way to fail is to die.
After a twist is resolved, it is exactly the same as if you had succeeded.
So given Plot ABCD…
If they fail A, they go to E, then E leads back to B
If they fail B, they go to either E or F, and then back to C.
My normal mode is a twist, and failing the twist, a condition, and on with the plot.