"The Movie Star" arrives to save the show ... and she can't sing! What?

That's just crazy, right? Eileen just took the word of her agent?!? For the musical, that was a problem, but for Smash, Rebecca Duvall's arrival brought smiles and laughs to the drama.

Her rendition of "Let Me Be Your Star" was horrendous. All Tom and Julia could say was "great" -- ha! And even that single word pained them. At least they didn't resort to Julia's suggestion of "group suicide."

The big question of how Ivy would be brought back into the fold was answered. Due to Rebecca's less than stellar beginning, they wanted their second backup right away, especially since their understudy is the very green Karen. I'm enjoying the growing friendship between Karen and Ivy. No one else understands what they are each going through better than the other. Going forward, they would benefit more from a friendship than viewing the other as a threat and an enemy. Since the pilot, I've been a fan of Karen's but recently, Ivy has grown on me.

She came into the production a diva, left the show disgruntled and bitter, but has returned a happier and friendlier Ivy. This Ivy is someone I want to root for to regain the role of Marilyn. She has shown she is talented and now she is beginning to show that she can be a star.

But, for now, Bombshell's Marilyn is Rebecca. She arrived confident and made herself known on arrival. Yet what initially appeared to be her testing or questioning the producers, writers and directors really was her trying to adjust the show to her strengths. She recognized her own weaknesses, but then eventually the strength of the show as it was.

At first, I was confused by her shift in attitude from the rehearsals and asking for rewrites to her acceptance of the script. In the end, at the group "pow-wow," she showed she is a professional. She pointed out a song that she couldn't sing, the octave that fit her voice the best, and acknowledged her need for a voice coach. At that point, she proved herself a team player.

While Rebecca was brought in for her movie star status, she ended up being much less of a diva than Ivy. She also had much less stage presence than either Ivy or Karen. To fill the seats, unfortunately they feel they need a big name, rather than a merely talented one.

Rebecca can sing and performed "Dig Deep" well, but she didn't have the appeal of Ivy or even Karen. That almost seemed by design, as her outfit for that number was almost frumpy and not sexy at all. Her voice was fine, but didn't have the depth of Ivy or Karen's.

The true test will be when we hear her take on tracks that Ivy and Karen have already performed. Will she be able to stand up to the high level that they have set or come even close? While it seems that Rebecca has locked the role, there is still a long way to go.

Besides, Derek keeps seeing Karen as Marilyn. What is up with that? Did Derek hit his head? Seriously, what the heck is up with him seeing Karen as Marilyn? Last week, I didn't mention it, because I figured it was a one-time thing. But this was over-the-top. An imagined song and performance? And in front of Ivy? Hmm ... what does it mean? I have no idea. It comes across as a poorly used mechanism for getting another song into the show. I doubt it will be the last time, either.

I wasn't expecting to like the arrival of Rebecca based on the previews, but it exceeded my expectations. Her character brought some much needed humor to offset some of darkness happening outside of the musical.

Carla Day is a staff writer for TV Fanatic. Follow her on Twitter and on Google+.