At a local college of engineering an unknown man in black steals a prototype weapon from the lab of a professor who, under contract with the US Department of Defense, specializes in nonnuclear electromagnetic pulses, which have the capability to render disastrous nonlethal damage; Callen and company investigate. G and Sam speak with the prof, who shows squirrelly behavior, and whom they catch in a lie, which leads to a major problem. Kensi returns to school. Eric meets Nell's family, and he finds a Gremlin but no pony. During a second break-in at the lab, someone grabs a second device, which can make the damage of the first one much worse. The team quickly put many pieces together, then they do some legwork, and the puzzle becomes complete; G and Sam do a task on a roof by night to bring the problem to an end. Back at the shop Hetty taps a keg, the gang toast and drink, Eric hands a gift to Sam, and Deeks hands one to Kensi.