Reese and Finch help a schoolteacher targeted by the mob after he witnesses a hit, and the identity of the mysterious Elias is revealed.

Finch and Reese team up with unexpected allies as they race to fix the machine; as Detective Carter tries to apprehend Cal Beecher's murderer, she finds herself up against HR -- a criminal organisation.

Finch and Reese have their work cut out protecting a grouchy, widower in his 70s with a grudge against a shady casino owner in Atlantic City.

Shaw must stay close to a 10-year-old girl with highly developed surveillance skills after she is identified by the machine; Carter's mission could be exposed.

The machine gives Finch 38 numbers at once; information about Carter's past is revealed.

Van Alden keeps tabs on Al Capone; Dr Valentin Narcisse clashes with Chalky and Nucky; Agent Knox aligns himself with J. Edgar Hoover; Harrow fails to finish a job; Eddie demands a promotion; Nucky leaves for Florida.

Nucky gets to know Arnold Rothstein over a card game; Eddie gets detoured after making a delivery; Al and Frank Capone finish a collector's route; Agent Knox vows to exploit Nucky's weakest link; Willie and his roommate take a practical joke too far.

Nucky heads to Philadelphia; Agent Knox detains Eddie Kessler to obtain information about Nucky's organisation; Gillian tries to score a fix; Van Alden is recruited by the Capones.

Hank, Beck, Arron and the Shepherds try to stop Lynch's plan and save Rachael before it's too late. The team makes an unimaginable discovery.

Hank's dream may reveal clues about Rachel's location. Theo and Vincent strike a deal. Hank, Beck and Arron travel to Tajikistan.

After a fellow inmate makes romantic advances, Piper's delicate approach in letting her down is not effective.