The original creditor is HSBC. Debt has been charged-off. Spoke with HSBC, they informed me they no longer have any information on this account and referred me to call the National Network Attorney. Gave them a call and they said the account has been assigned to Mann Bracken LLP. Does that mean Mann Bracken now owns the account? If I get a summons of complaint regarding this debt, who should be named as the Plaintiff? HSBC or Mann Bracken?

What difference does it make?

The answer is that probably HSBC will be the plaintiff but the debt is still as valid if they aren't. Some companies will sell the debt, some will retain it and contract outside collections for a portion of the amount owed or recovered.

Charge off is an accounting term and has little to do with debt ownership. It is more for tax purposes.

HSBC may be mentioned as the plaintiff or the creditor. But as Steve said, what does it matter? As long as Mann Bracken can prove they are entitled to collect on this debt either by assignment or purchase, then the issue is moot.

... they said the account has been assigned to Mann Bracken LLP. Does that mean Mann Bracken now owns the account? ...

Yes. As others have said in this thread, if MB can prove they have been assigned the account they do in fact own it and can sue you in their own name.