Bridget Jones (Renée Zellweger) is still all by herself in the trailer for the third installment in her single-lady saga, Bridget Jones's Baby. But this time, Bridget is telling the song "All by Myself" — which yielded one of the first movie's most memorable moments — to "screw off."There's another part of Bridget's life that hasn't changed in the 12 years since we last saw her. She's embroiled in a love triangle! And now there's a baby involved. You see, Colin Firth's Mark Darcy — still dreamy as ever — is still around, even though he and Bridget broke up. Meanwhile, the trailer teases a muddy meet cute with Jack Qwant, played by McDreamy himself, Patrick Dempsey. Hence, when Bridget discovers she's pregnant, she doesn't know which of these handsome men is the father. (One guy we know it probably isn't: Ed Sheeran, who makes a cameo appearance.)Naturally, this leads to hijinks. Bridget even has her doctor (a delightfully exasperated Emma Thompson) perform a sonogram for each man.So, who is it? Apparently, the cast doesn't even know , as they filmed three different endings. The movie comes out in September. Check out the trailer, below.