The boss bludgeoned the employees into working overtime with threats of firing.

bludgeoned 是动词 bludgeon 的过去式。bludgeon 原指"用棍棒殴打"，引申为"强迫、胁迫"的意思，表示用暴力或威胁手段迫使某人做某事。这里指老板用解雇威胁这种强硬手段逼迫员工加班。