The series picks up just after Riggs gets shot at the end of season two, and we find out within the first episode that he died, then there is a six-month time jump and we find out that his brother committed suicide, and that was it for the Riggs storyline (aside from a couple of throwaway lines during the season that mentioned him). The series then focuses on the new Lethal Weapon, an ex-CIA agent named Wesley Cole (played by Sean William Scott), who is new to the department trying to put his past behind him and connect with his 12-year-old daughter.
It is mostly again, a case-of-the-week series, but there are a couple of storylines that play out across multiple episodes. I do think Scott did a great job with the character of Cole. Given that he has mostly played Stifler or slight variations of Stifler his entire career (with a couple of exceptions), this showed he has a range beyond the raunchy comedies. Maggie Lawson (best known for the series Psych) was another good addition to the cast as Cole's ex-wife who is trying to put her past with Cole behind her, yet still, have an amicable relationship with him for the sake of their daughter. One major defection from the cast (aside from Crawford) was Jordana Brewster, who basically left the show after a couple of episodes.
It is a fairly standard MOD set for those who get the blu-ray set. The fifteen episodes are spread over three discs. It has captions and a true "play all" mode that allows you to pick back up where you stop, even in the middle of an episode. There are no extras like commentary tracks, making-of, deleted scenes, or behind-the-scenes material. It did try to keep a similar feel to the prior two seasons, and I think the writers and cast did the best they could, given the mess they had going into the third season. However, it was not the same show without the character of Riggs.