If you aren't familiar with Transplants, you might be surprised to hear how assuredly they attack their aggressive mix of punk, pop, and hard rock. But one look at who's in the group should explain it all. That's Rancid's Tim Armstrong and Blink-182's Travis Barker working with their buddy Rob Aston on a side project that's as much fun as their day jobs. The group formed in 2002 and immediately put out a strong self-titled debut, with the follow-up, Haunted Cities, coming in 2005. Eight years later, Transplants' third album, In a Warzone, has arrived. Here, Aston does much less of his old rap style, which only shows up on the near–easy listening "Something's Different" and the rap-rock "It's a Problem." The band mostly focuses on its roots. Old-school punk rage gives tunes such as the title track, "Any of Them," "Silence," and "See It to Believe It" an energy that recalls the best aspects of the late '70s, the early '80s, and the first punk revival in the '90s. There's not a bum track here. Transplants keep it relatively simple and work with great guitar sounds that don't bury the drums or the vocals.