Underplot and Interpose

• (n.) A clandestine scheme; a trick.
• (n.) A series of events in a play, proceeding collaterally with the main story, and subservient to it.

verb

• Be or come between.
  • usage: "An interposing thicket blocked their way"
• Introduce.
  • usage: "God interposed death"
• To insert between other elements.
  • usage: "She interjected clever remarks"
  • synonyms: interject, come in, put in, throw in, inject
• Get involved, so as to alter or hinder an action, or through force or threat of force.
  • usage: "Why did the U. S. Not intervene earlier in WW II"
  • synonyms: intervene, step in, interfere

• (n.) Interposition.
• (v.t.) To introduce or inject between the parts of a conversation or argument.
• (v.i.) To step in between parties at variance; to mediate; as, the prince interposed and made peace.
• (v.i.) To utter a sentiment by way of interruption.
• (v.t.) To thrust; to intrude; to between, either for aid or for troubling.
• (v.t.) To place between; as, to interpose a screen between the eye and the light.
• (v.i.) To be or come between.