How are pennies useful?

Smith puts an end to the plot, causing the death of Captain Kendall.

Explanation:

In the passage, there was a discussion between Kendall and Wingfield. They developed a plan and decided to executive the plan. However, Smith was able to find out about their plan. Smith thought carefully about the best thing to do to put an end to their plan. Smith was able to put an end to their plan and it led to Captain Kendall's death.