Garner Goes Undercover – for Good

By Marla Lehner

11/25/2005 at 08:40 AM EST

Jennifer Garner has apparently gone on her last spy mission: the star's ABC espionage drama, Alias will air its final episode in May.

Garner, who is expecting her first child with husband Ben Affleck next month, played the butt-kicking, globe-trotting Sydney Bristow for five seasons. Though she still donned disguises and foiled the bad guys this year, her sexy spy persona was hampered a bit by her clearly growing belly.

"No more short skirts or high boots," an Alias source told PEOPLE. "She's just too big!"

But Garner's real-life pregnancy was written into the script and instead of camouflaging her condition, she continued to vamp it up until Nov. 18, when she went on maternity leave.

Alias's ratings have sharply declined since it moved to a tougher time slot on Thursdays this season. However, in classic Alias style, ABC promises the show won't "wind down as it comes to an end." Instead, "it's going to rev up, and we're going to make it the event it deserves to be," ABC Entertainment President Stephen McPherson said in a statement Wednesday.

As for Garner, she has her biggest adventure of all still to come: motherhood.