It is the 70th overall episode of the series and is written by Dan Dietz and Melissa Scrivner Love and directed by co-executive producer Chris Fisher.
The series revolves around a computer program for the federal government known as "The Machine" that is capable of collating all sources of information to predict terrorist acts and to identify people planning them.
A team, consisting of John Reese, Harold Finch and Sameen Shaw follow "irrelevant" crimes: lesser level of priority for the government.
According to Nielsen Media Research, the episode was seen by an estimated 10.72 million household viewers and gained a 1.8/6 ratings share among adults aged 18–49.
However, Reese reveals that he is not attending and he only sent Finch so he could check their new number: Claire Mahoney (Quinn Shephard), a very intelligent young mathematician.
In its original American broadcast, "Nautilus" was seen by an estimated 10.72 million household viewers and gained a 1.8/6 ratings share among adults aged 18–49, according to Nielsen Media Research.
Matt Fowler of IGN gave the episode an "amazing" 9 out of 10 rating and wrote in his verdict, "'Nautilus' was smart, fun, and strikingly ominous.
It provided a haunting reminder of how dangerously ahead-of-the-curve Samaritan is while showing Finch that things will only get worse if he remained on the sidelines.
Club gave the episode an "A−" grade and wrote, "'Nautilus' starts off slowly, but like any good puzzle, it finishes satisfactorily once all of the pieces have been put into their proper places.