Complex sentence: Eager and willing, the two set out to tackle a series of cases--mimicking in each the style of a famous fictional detective of the period, including Sherlock Holmes and Christie's own Hercule Poirot.
Split into simpler sentences: Eager and willing, the two set out to tackle several cases. In each case mimicking the style of a famous fictional detective of the period, including Sherlock Holmes and Christie's own Hercule Poirot.