Over the years, I’ve found it’s less helpful to think of the campaign as a planned road trip - and more helpful to think about it like you’re in a car chase and your brakes have been cut.

Don’t plan out meticulously, just prioritize steering into the next interesting thing that can happen, ideally one that the party is already kinda heading towards. You can have some ideas about things that could happen afterward, but you have no idea what your players will do yet.

They could befriend the lich’s minions, commit the crime before the villain has a chance to, or just straight up die to terrible luck.