During the Renaissance, English writers often depict poison as a weapon capable of transforming a victim's body into a timepiece, with death predictable to the year, month, day, and hour. English literary works, especially dramatic ones, however, contain numerous instances of poisons that fail to act precisely, or to act as intended. These failures serve as a useful departure point for exploring Renaissance ideas of clock-time. The dream of temporal control represented by poison promises an alignment between timepieces and bodies. When poisons fail to create this promised synchronicity, they reveal both the interdependence of bodies and horological devices and the difficulties in regulating either one.