Ted joins a dating agency with a remarkable success record in an attempt to meet the love of his life. Back at home, Marshall and Lily wage war with a household pest, which seems to be part mouse, part cockroach.
Meredith and Cristina bicker about their careers; Bailey talks to Ben about him moving back to Seattle; Shane puts himself in a risky situation; Derek receives a life-changing phone call.
The unit welcome a new member to the team, before travelling to Washington where the remains of 12 people are found along a creek bed.
Castle and Beckett investigate the murder of a man stuffed down a garbage shoot. Things get complicated when both his wife and fiancé come in to identify the body.
Pope suggests that the Sons should increase their drug-trafficking business, an operation he will fund. Elsewhere, Roosevelt's wife dies from the gunshot wound she received when her house was broken into.