A sub-plot is an important tool for adding depth to any novel. As you sort out the storyline for your novel, it’s important that you enrich your main plot with these elements. Let’s, however, begin with a helpful definition of a sub-plot: Sub-plots are secondary storylines. They are distinct from the main plot but they complement it. The main plot and sub-plots inter-connect, and the sub-plots help clarify the main story. The can also offer opportunities to learn more about the characters and their personal story.
Let’s try our hand at a plot and a sub-plot that eventually mesh into the main storyline. An adulterous husband wants to kill his adulterous wife for the life insurance, so he hires a hit man. After the deed it done, a fetching female homicide detective is assigned to solve the case. That’s the plot. The sub-plot? The fetching female homicide detective is fighting her own battles at home, with a failing marriage and abhorrent husband. She must solve the crime while dealing with her own personal struggles. So, how do we bring these two stories together? How about this? The detective solves the crime, but in the process falls in love with the hit man and gets him to kill both her husband and the murderous creep from the main plot. They then live happily ever after. Wait, there’s a sub-sub plot to be resolved. The hit man’s adorable young love-child daughter stumbles onto the situation, and she must deal with the conflict between her moral duty and her love for her father and . . . oh, you get it, don’t you?
What if it’s not a Murder Mystery? Sub-plots can, and should occur in any genre. A heroic doctor is trying to find a cure for a terrible disease that is ravaging a poor, third-world tribe. The main plot details the trials and tribulations that he must suffer in order to make the cure a reality. At one point, in order to prove the efficacy of the experimental cure, he injects himself with the virus that causes the disease. Will he be cured, or will he end up making the ultimate sacrifice for nothing? Unbeknownst to our hero, a local chieftain encounters stiff resistance from the tribe’s elders because he is struggling with feeling unnecessary. The doctor attempts to educate his superstitious people to understand that the disease cannot be cured by the “venerable” witch doctor’s prescription, human sacrifice, and the people struggle with accepting an outsider’s help and ignoring centuries of their own traditions. In the end, the plot and sub-plots come together to provide a happy or tragic ending. (That’s the fun part- you as the writer get to decide which.)
Constructing the sub-plots you want to use can be done in your initial outline, but often they’ll come to you in a fit of inspiration as you write your book. Don’t reject them. If an additional sub-plot adds value, it’s worth the challenge of incorporating it.