Do we need a crisis plan?

Less than you think. A plan often becomes outdated the very moment a crisis occurs. A clear structure for who does what lasts longer.

What is usually lacking are simple things: who makes decisions, who speaks, who informs employees, and how you reach each other outside of office hours.

That structure can be put in place quickly and it holds up no matter what happens. Practice it once a year, and it will be there when it is needed.