Watch the sneak peek for Monday’s How I Met Your Mother episode “Ring Up!” in which we meet Carly (played by Ashley Benson).

In the sneak peek, we see Ted tell the gang about his new girlfriend – his very young college girlfriend, played by Pretty Little Liars star Ashley Benson.

Barney will be very supportive of this relationship, but we’re willing to bet that this is only until he finds out who this Carly really is. That’s right, Barney’s half-sister! It was long speculated that Carly could be the mother, but now that doesn’t seem to be the case, as we’ve pretty much seen Ted meeting the mother at Barney and Robin’s wedding at this point.

A brief synopsis of the upcoming episode 8×15 “P.S. I Love You” has also been revealed. This will be the last instalment of the Robin Sparkles saga, and while we’re sad there won’t be any more flashbacks for the teenage pop sensation, we can’t wait for this one:

P.S. I Love You” —Barney uncovers the lost episode of Robin’s “Underneath the Tunes” as Robin Sparkles. Meanwhile, Marshall and Lily are concerned that Ted’s new girlfriend is a stalker.

How I Met Your Mother 8×14 “Ring Up!” airs Monday at 8/7c on CBS. Are you looking forward to meeting Carly?