With a routine planetary survey ahead, the Federation starship "Enterprise" drops Commander Riker (Jonathan Frakes) and Chief Engineer La Forge (LeVar Burton) at the Botanica Four research space station orbiting Tanuga Four to check on the progress of the work of Dr. Nel Apgar (Mark Margolis), a Tanugan who has been working on Krieger waves, a new promised energy source for the Federation. When the "Enterprise" returns, Captain Picard (Patrick Stewart) is told that Riker stayed behind to have a private meeting with Apgar, and moments after Riker transports back to the ship, the station explodes, killing Apgar, and almost killing Riker due to the explosion disrupting the transporter process. Tanugan investigator Krag (Craig Richard Nelson) comes aboard to accuse Riker of murder; under Tanugan law, Riker is guilty until proven innocent, and Krag demands Riker's extradition. Captain Picard requests that they hold a hearing aboard the "Enterprise" to determine Riker's guilt. This involves the use of a holodeck, recreating the events on the station from data logs and testimony from Riker, Dr. Apgar's wife Manua (Gina Hecht), and his research assistant, Tayna (Juliana Donald).